[syzbot] [squashfs?] KASAN: slab-out-of-bounds Write in squashfs_readahead (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 13d88ac54ddd Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=121965ef680000
kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12b40c7b680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10f691ef680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9e81dc4903c2/disk-13d88ac5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f40fd7326b3f/vmlinux-13d88ac5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f399cd6ff7d/bzImage-13d88ac5.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8e127c645a04/mount_0.gz

The issue was bisected to:

commit f268eedddf3595e85f8883dc50aed29654785696
Author: Phillip Lougher <phi...@squashfs.org.uk>
Date: Sat Jun 11 03:21:32 2022 +0000

squashfs: extend "page actor" to handle missing pages

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1252b717680000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1152b717680000
console output: https://syzkaller.appspot.com/x/log.txt?x=1652b717680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+604424...@syzkaller.appspotmail.com
Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")

SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
==================================================================
BUG: KASAN: slab-out-of-bounds in __readahead_batch include/linux/pagemap.h:1364 [inline]
BUG: KASAN: slab-out-of-bounds in squashfs_readahead+0x9a6/0x20d0 fs/squashfs/file.c:569
Write of size 8 at addr ffff88801e393648 by task syz-executor100/5067

CPU: 1 PID: 5067 Comm: syz-executor100 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x142/0x170 mm/kasan/report.c:588
__readahead_batch include/linux/pagemap.h:1364 [inline]
squashfs_readahead+0x9a6/0x20d0 fs/squashfs/file.c:569
read_pages+0x183/0x830 mm/readahead.c:160
page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f0e73d6c5f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd516ff158 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f0e73d6c5f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0
RBP: 00007f0e73ddf610 R08: 0000000000000225 R09: 0000000000000000
R10: 00007ffd516ff020 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffd516ff328 R14: 0000000000000001 R15: 0000000000000001
</TASK>

Allocated by task 5067:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1007 [inline]
__kmalloc+0xb9/0x230 mm/slab_common.c:1020
kmalloc_array include/linux/slab.h:637 [inline]
squashfs_readahead+0x30c/0x20d0 fs/squashfs/file.c:552
read_pages+0x183/0x830 mm/readahead.c:160
page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

The buggy address belongs to the object at ffff88801e393640
which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of
allocated 8-byte region [ffff88801e393640, ffff88801e393648)

The buggy address belongs to the physical page:
page:ffffea000078e4c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801e393230 pfn:0x1e393
anon flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888012c41280 0000000000000000 dead000000000001
raw: ffff88801e393230 0000000080660063 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 10649202635, free_ts 9358727270
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
prep_new_page mm/page_alloc.c:1544 [inline]
get_page_from_freelist+0x339a/0x3530 mm/page_alloc.c:3312
__alloc_pages+0x255/0x670 mm/page_alloc.c:4568
alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
alloc_slab_page+0x6a/0x160 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc85/0x1310 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x21d/0x300 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1027
kstrdup+0x3a/0x70 mm/util.c:62
__kernfs_new_node+0x9d/0x870 fs/kernfs/dir.c:611
kernfs_new_node+0x99/0x170 fs/kernfs/dir.c:679
kernfs_create_link+0xa5/0x1f0 fs/kernfs/symlink.c:39
sysfs_do_create_link_sd+0x85/0x100 fs/sysfs/symlink.c:44
device_create_sys_dev_entry+0x10f/0x170 drivers/base/core.c:3451
device_add+0x8cf/0xd30 drivers/base/core.c:3595
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1137 [inline]
free_unref_page_prepare+0x92a/0xa50 mm/page_alloc.c:2347
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
vfree+0x186/0x2e0 mm/vmalloc.c:2842
delayed_vfree_work+0x56/0x80 mm/vmalloc.c:2763
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703
worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784
kthread+0x2d3/0x370 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

Memory state around the buggy address:
ffff88801e393500: 00 fc fc fc fc fa fc fc fc fc 05 fc fc fc fc 05
ffff88801e393580: fc fc fc fc 00 fc fc fc fc 05 fc fc fc fc fa fc
>ffff88801e393600: fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc
^
ffff88801e393680: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
ffff88801e393700: fc 00 fc fc fc fc fb fc fc fc fc 00 fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ba8c4c50770..c91a37be5589 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -553,6 +553,9 @@ static void squashfs_readahead(struct readahead_control *ractl)
if (!pages)
return;

+ printk("p: %p, bs: %d, bl: %d, mp: %d, start: %d, fe: %d, %s\n",
+ pages, msblk->block_size, msblk->block_log,
+ max_pages, start, file_end, __func__);
for (;;) {
pgoff_t index;
int res, bsize;
@@ -566,6 +569,8 @@ static void squashfs_readahead(struct readahead_control *ractl)

max_pages = (expected + PAGE_SIZE - 1) >> PAGE_SHIFT;

+ printk("p: %p, mp: %d, e: %d, idx: %d, s: %d, %s\n", pages, max_pages,
+ expected, pages[0]->index, start, __func__);
nr_pages = __readahead_batch(ractl, pages, max_pages);
if (!nr_pages)
break;
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 22e812808e5c..aad49a62b5ce 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -275,6 +275,8 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
goto failed_mount;

+ printk("bs: %d, bl: %d, %s\n", msblk->block_size, msblk->block_log, __func__);
+
/* Check that block_size and block_log match */
if (msblk->block_size != (1 << msblk->block_log))
goto insanity;

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in squashfs_readahead

SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]

p: ffff888020f895a0, bs: 4096, bl: 12, mp: 1, start: 0, fe: 0, squashfs_readahead
general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 PID: 5475 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

RIP: 0010:squashfs_readahead+0x5a1/0x1dd0 fs/squashfs/file.c:572
Code: 89 84 24 10 01 00 00 42 80 3c 30 00 74 08 4c 89 ef e8 e3 06 8d ff 48 c1 2c 24 0c 49 8b 5d 00 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 c0 06 8d ff 4c 8b 03 48 c7 c7 60
RSP: 0018:ffffc900052c6380 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000000000020 RCX: ffff888019ac0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900052c65b0 R08: ffffffff825dd62d R09: 1ffff92000a58c0c
R10: dffffc0000000000 R11: fffff52000a58c0d R12: ffffc900052c6998
R13: ffff888020f895a0 R14: dffffc0000000000 R15: ffffc900052c64e0
FS: 00007fc5c7f106c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005649916ab2e8 CR3: 00000000209b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

read_pages+0x183/0x830 mm/readahead.c:160
page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

RIP: 0033:0x7fc5c727cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc5c7f100c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fc5c739bf80 RCX: 00007fc5c727cae9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0

RBP: 00007fc5c72c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fc5c739bf80 R15: 00007ffd8245e0c8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:squashfs_readahead+0x5a1/0x1dd0 fs/squashfs/file.c:572
Code: 89 84 24 10 01 00 00 42 80 3c 30 00 74 08 4c 89 ef e8 e3 06 8d ff 48 c1 2c 24 0c 49 8b 5d 00 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 c0 06 8d ff 4c 8b 03 48 c7 c7 60
RSP: 0018:ffffc900052c6380 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000000000020 RCX: ffff888019ac0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900052c65b0 R08: ffffffff825dd62d R09: 1ffff92000a58c0c
R10: dffffc0000000000 R11: fffff52000a58c0d R12: ffffc900052c6998
R13: ffff888020f895a0 R14: dffffc0000000000 R15: ffffc900052c64e0
FS: 00007fc5c7f106c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005649916ab2e8 CR3: 00000000209b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 89 84 24 10 01 00 00 mov %eax,0x110(%rsp)
7: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
c: 74 08 je 0x16
e: 4c 89 ef mov %r13,%rdi
11: e8 e3 06 8d ff call 0xff8d06f9
16: 48 c1 2c 24 0c shrq $0xc,(%rsp)
1b: 49 8b 5d 00 mov 0x0(%r13),%rbx
1f: 48 83 c3 20 add $0x20,%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 48 89 df mov %rbx,%rdi
34: e8 c0 06 8d ff call 0xff8d06f9
39: 4c 8b 03 mov (%rbx),%r8
3c: 48 rex.W
3d: c7 .byte 0xc7
3e: c7 (bad)
3f: 60 (bad)


Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1407c024e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=12723810e80000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c

index 8ba8c4c50770..a60c2be4447e 100644

--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -553,6 +553,9 @@ static void squashfs_readahead(struct readahead_control *ractl)
if (!pages)
return;

+ printk("p: %p, bs: %d, bl: %d, mp: %d, start: %d, fe: %d, %s\n",
+ pages, msblk->block_size, msblk->block_log,
+ max_pages, start, file_end, __func__);
for (;;) {
pgoff_t index;
int res, bsize;
@@ -566,6 +569,8 @@ static void squashfs_readahead(struct readahead_control *ractl)

max_pages = (expected + PAGE_SIZE - 1) >> PAGE_SHIFT;

+ printk("p: %p, mp: %d, e: %d,isr: %d, start: %d, %s\n", pages, max_pages,
+ expected, i_size_read(inode), start, __func__);

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

KASAN: slab-out-of-bounds Write in squashfs_readahead

SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]

p: ffff88801ea30b18, bs: 4096, bl: 12, mp: 1, start: 0, fe: 0, squashfs_readahead
p: ffff88801ea30b18, mp: 0, e: 0,isr: 0, start: 0, squashfs_readahead

==================================================================
BUG: KASAN: slab-out-of-bounds in __readahead_batch include/linux/pagemap.h:1364 [inline]

BUG: KASAN: slab-out-of-bounds in squashfs_readahead+0xa5a/0x1de0 fs/squashfs/file.c:574
Write of size 8 at addr ffff88801ea30b20 by task syz-executor.0/5481

CPU: 1 PID: 5481 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x142/0x170 mm/kasan/report.c:588
__readahead_batch include/linux/pagemap.h:1364 [inline]

squashfs_readahead+0xa5a/0x1de0 fs/squashfs/file.c:574

read_pages+0x183/0x830 mm/readahead.c:160
page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

RIP: 0033:0x7f57b767cae9

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f57b84070c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f57b779bf80 RCX: 00007f57b767cae9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0

RBP: 00007f57b76c847a R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 000000000000000b R14: 00007f57b779bf80 R15: 00007ffd5c197a58
</TASK>

Allocated by task 5481:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1007 [inline]
__kmalloc+0xb9/0x230 mm/slab_common.c:1020
kmalloc_array include/linux/slab.h:637 [inline]

squashfs_readahead+0x2e8/0x1de0 fs/squashfs/file.c:552

read_pages+0x183/0x830 mm/readahead.c:160
page_cache_ra_unbounded+0x68e/0x7c0 mm/readahead.c:269
page_cache_sync_readahead include/linux/pagemap.h:1266 [inline]
filemap_get_pages+0x49c/0x2080 mm/filemap.c:2497
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

The buggy address belongs to the object at ffff88801ea30b18

which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of

allocated 8-byte region [ffff88801ea30b18, ffff88801ea30b20)

The buggy address belongs to the physical page:

page:ffffea00007a8c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ea30

flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()

raw: 00fff00000000800 ffff888012c41280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY), pid 25, tgid 25 (kdevtmpfs), ts 8927536691, free_ts 8917015211

set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
prep_new_page mm/page_alloc.c:1544 [inline]
get_page_from_freelist+0x339a/0x3530 mm/page_alloc.c:3312
__alloc_pages+0x255/0x670 mm/page_alloc.c:4568
alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
alloc_slab_page+0x6a/0x160 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc85/0x1310 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x21d/0x300 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1027

kstrndup+0x41/0xb0 mm/util.c:108
smk_parse_smack security/smack/smack_access.c:468 [inline]
smk_import_entry+0x18d/0x610 security/smack/smack_access.c:563
smk_fetch+0xdd/0x140 security/smack/smack_lsm.c:310
smack_d_instantiate+0x74a/0xa50 security/smack/smack_lsm.c:3573
security_d_instantiate+0x9b/0xf0 security/security.c:3799
d_instantiate+0x55/0x90 fs/dcache.c:2033
shmem_mknod+0x191/0x1c0 mm/shmem.c:3246

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1137 [inline]
free_unref_page_prepare+0x92a/0xa50 mm/page_alloc.c:2347
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487

mm_free_pgd kernel/fork.c:803 [inline]
__mmdrop+0xb8/0x3d0 kernel/fork.c:919
free_bprm+0x144/0x330 fs/exec.c:1490
kernel_execve+0x8f5/0xa10 fs/exec.c:2024
call_usermodehelper_exec_async+0x233/0x370 kernel/umh.c:110

ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

Memory state around the buggy address:

ffff88801ea30a00: 06 fc fc fc fc fb fc fc fc fc 00 fc fc fc fc fb
ffff88801ea30a80: fc fc fc fc fb fc fc fc fc fb fc fc fc fc fa fc
>ffff88801ea30b00: fc fc fc 00 fc fc fc fc fb fc fc fc fc 06 fc fc
^
ffff88801ea30b80: fc fc 06 fc fc fc fc fb fc fc fc fc fb fc fc fc
ffff88801ea30c00: fc fb fc fc fc fc fb fc fc fc fc 06 fc fc fc fc
==================================================================

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=139741a7680000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=12214824e80000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c

index 8ba8c4c50770..cb3753782d85 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -566,6 +566,8 @@ static void squashfs_readahead(struct readahead_control *ractl)

max_pages = (expected + PAGE_SIZE - 1) >> PAGE_SHIFT;

+ if (!max_pages)
+ break;

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

general protection fault in squashfs_page_actor_init_special

SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 5484 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

RIP: 0010:squashfs_page_actor_init_special+0x20e/0x4c0 fs/squashfs/page_actor.c:128
Code: 00 00 00 49 8d 6c 24 48 48 89 e8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 32 02 00 00 c7 45 00 00 00 00 00 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 93 34 8c ff 49 8b 2f 48 83 c5 20
RSP: 0018:ffffc90004fce4f8 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffff888015ad3b80
RDX: ffff888015ad3b80 RSI: 0000000000000000 RDI: ffff888027646840
RBP: ffff888027646848 R08: ffffffff825ea873 R09: 1ffffffff21ba48f
R10: dffffc0000000000 R11: fffffbfff21ba490 R12: ffff888027646800
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000010
FS: 00007f7b9e9ea6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f7b9dd0662e CR3: 0000000020cfe000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

squashfs_readpage_block+0x62a/0xf60 fs/squashfs/file_direct.c:70
squashfs_read_folio+0x569/0xed0 fs/squashfs/file.c:479
filemap_read_folio+0x19c/0x770 mm/filemap.c:2323
filemap_create_folio mm/filemap.c:2451 [inline]
filemap_get_pages+0xdf7/0x2080 mm/filemap.c:2504

filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

RIP: 0033:0x7f7b9dc7cae9

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f7b9e9ea0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7b9dd9bf80 RCX: 00007f7b9dc7cae9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0

RBP: 00007f7b9dcc847a R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 000000000000000b R14: 00007f7b9dd9bf80 R15: 00007fff0acb6118

</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

RIP: 0010:squashfs_page_actor_init_special+0x20e/0x4c0 fs/squashfs/page_actor.c:128
Code: 00 00 00 49 8d 6c 24 48 48 89 e8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 32 02 00 00 c7 45 00 00 00 00 00 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 93 34 8c ff 49 8b 2f 48 83 c5 20
RSP: 0018:ffffc90004fce4f8 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffff888015ad3b80
RDX: ffff888015ad3b80 RSI: 0000000000000000 RDI: ffff888027646840
RBP: ffff888027646848 R08: ffffffff825ea873 R09: 1ffffffff21ba48f
R10: dffffc0000000000 R11: fffffbfff21ba490 R12: ffff888027646800
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000010
FS: 00007f7b9e9ea6c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000555d54061950 CR3: 0000000020cfe000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):

0: 00 00 add %al,(%rax)
2: 00 49 8d add %cl,-0x73(%rcx)
5: 6c insb (%dx),%es:(%rdi)
6: 24 48 and $0x48,%al
8: 48 89 e8 mov %rbp,%rax
b: 48 c1 e8 03 shr $0x3,%rax
f: 42 0f b6 04 30 movzbl (%rax,%r14,1),%eax
14: 84 c0 test %al,%al
16: 0f 85 32 02 00 00 jne 0x24e
1c: c7 45 00 00 00 00 00 movl $0x0,0x0(%rbp)
23: 4c 89 f8 mov %r15,%rax

26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction
2f: 74 08 je 0x39

31: 4c 89 ff mov %r15,%rdi
34: e8 93 34 8c ff call 0xff8c34cc
39: 49 8b 2f mov (%r15),%rbp
3c: 48 83 c5 20 add $0x20,%rbp

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=10ed2f97680000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=17f132ff680000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c

index 8ba8c4c50770..0a586a7f470e 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -547,6 +547,9 @@ static void squashfs_readahead(struct readahead_control *ractl)
int i, file_end = i_size_read(inode) >> msblk->block_log;
unsigned int max_pages = 1UL << shift;

+ if (!file_end && !start)
+ return;
+
readahead_expand(ractl, start, (len | mask) + 1);

pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c
index f1ccad519e28..9c167df9248d 100644
--- a/fs/squashfs/file_direct.c
+++ b/fs/squashfs/file_direct.c
@@ -35,6 +35,9 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
struct squashfs_page_actor *actor;
void *pageaddr;

+ if (!file_end)
+ return -EINVAL;
+
if (end_index > file_end)
end_index = file_end;

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in squashfs_page_actor_init_special

SQUASHFS error: Failed to read block 0x6fc: -5

SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
SQUASHFS error: Unable to read metadata cache entry [6fa]
general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]

CPU: 1 PID: 5484 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15156-g13d88ac54ddd-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:squashfs_page_actor_init_special+0x20e/0x4c0 fs/squashfs/page_actor.c:128

Code: 00 00 00 49 8d 6c 24 48 48 89 e8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 32 02 00 00 c7 45 00 00 00 00 00 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 73 34 8c ff 49 8b 2f 48 83 c5 20
RSP: 0018:ffffc9000504e4f8 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffff888023400000
RDX: ffff888023400000 RSI: 0000000000000000 RDI: ffff88801d0c0f40
RBP: ffff88801d0c0f48 R08: ffffffff825ea893 R09: 1ffffffff21ba48f
R10: dffffc0000000000 R11: fffffbfff21ba490 R12: ffff88801d0c0f00

R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000010

FS: 00007f371f1fe6c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000562a2771d950 CR3: 0000000023dac000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

squashfs_readpage_block+0x659/0xf90 fs/squashfs/file_direct.c:73

squashfs_read_folio+0x569/0xed0 fs/squashfs/file.c:479
filemap_read_folio+0x19c/0x770 mm/filemap.c:2323
filemap_create_folio mm/filemap.c:2451 [inline]
filemap_get_pages+0xdf7/0x2080 mm/filemap.c:2504
filemap_read+0x42b/0x10b0 mm/filemap.c:2593
__kernel_read+0x425/0x8b0 fs/read_write.c:428
integrity_kernel_read+0xb0/0xf0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xad1/0x1b30 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x554/0xb30 security/integrity/ima/ima_api.c:290
process_measurement+0x1373/0x21c0 security/integrity/ima/ima_main.c:359
ima_file_check+0xf1/0x170 security/integrity/ima/ima_main.c:557
do_open fs/namei.c:3624 [inline]
path_openat+0x2893/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_open fs/open.c:1463 [inline]
__se_sys_open fs/open.c:1459 [inline]
__x64_sys_open+0x225/0x270 fs/open.c:1459
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

RIP: 0033:0x7f371fe7cae9

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f371f1fe0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f371ff9bf80 RCX: 00007f371fe7cae9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0

RBP: 00007f371fec847a R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 000000000000000b R14: 00007f371ff9bf80 R15: 00007fff173cbda8

</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:squashfs_page_actor_init_special+0x20e/0x4c0 fs/squashfs/page_actor.c:128

Code: 00 00 00 49 8d 6c 24 48 48 89 e8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 32 02 00 00 c7 45 00 00 00 00 00 4c 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 08 4c 89 ff e8 73 34 8c ff 49 8b 2f 48 83 c5 20
RSP: 0018:ffffc9000504e4f8 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffff888023400000
RDX: ffff888023400000 RSI: 0000000000000000 RDI: ffff88801d0c0f40
RBP: ffff88801d0c0f48 R08: ffffffff825ea893 R09: 1ffffffff21ba48f
R10: dffffc0000000000 R11: fffffbfff21ba490 R12: ffff88801d0c0f00

R13: 0000000000000000 R14: dffffc0000000000 R15: 0000000000000010

FS: 00007f371f1fe6c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000562a2771d950 CR3: 0000000023dac000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 49 8d add %cl,-0x73(%rcx)
5: 6c insb (%dx),%es:(%rdi)
6: 24 48 and $0x48,%al
8: 48 89 e8 mov %rbp,%rax
b: 48 c1 e8 03 shr $0x3,%rax
f: 42 0f b6 04 30 movzbl (%rax,%r14,1),%eax
14: 84 c0 test %al,%al
16: 0f 85 32 02 00 00 jne 0x24e
1c: c7 45 00 00 00 00 00 movl $0x0,0x0(%rbp)
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi

34: e8 73 34 8c ff call 0xff8c34ac

39: 49 8b 2f mov (%r15),%rbp
3c: 48 83 c5 20 add $0x20,%rbp


Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=1637eba8e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1139bf88e80000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd


diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c

index 8ba8c4c50770..e6dc2a5a8bcd 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -461,6 +461,11 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
page->index, squashfs_i(inode)->start);

+ if (!file_end) {
+ res = -EINVAL;
+ goto out;
+ }
+
if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
PAGE_SHIFT))
goto out;
@@ -547,6 +552,9 @@ static void squashfs_readahead(struct readahead_control *ractl)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=150f2170e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=12214020e80000

Note: testing is done by a robot and is best-effort only.

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c

index 8ba8c4c50770..b54d6b993357 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -461,6 +461,12 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)

TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
page->index, squashfs_i(inode)->start);

+ if (!file_end) {

+ printk("i:%p, is:%d, %s\n", inode, i_size_read(inode), __func__);

+ res = -EINVAL;
+ goto out;
+ }
+
if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
PAGE_SHIFT))
goto out;

@@ -547,6 +553,11 @@ static void squashfs_readahead(struct readahead_control *ractl)

int i, file_end = i_size_read(inode) >> msblk->block_log;
unsigned int max_pages = 1UL << shift;

+ if (!file_end && !start) {

+ printk("i:%p, is:%d, %s\n", inode, i_size_read(inode), __func__);
+ return;
+ }

+
readahead_expand(ractl, start, (len | mask) + 1);

pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);

diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
index aa3411354e66..680d8b302e60 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -125,6 +125,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
offset = SQUASHFS_INODE_OFFSET(ino);

type = le16_to_cpu(sqshb_ino->inode_type);
+ printk("in: %p, fs: %d, it: %d, %s\n", inode, le32_to_cpu(sqsh_ino->file_size), type, __func__);
switch (type) {
case SQUASHFS_REG_TYPE: {
unsigned int frag_offset, frag;

[Phillip Lougher]

On Sun, Nov 12, 2023 at 5:32 AM syzbot
<syzbot+604424...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 13d88ac54ddd Merge tag 'vfs-6.7.fsid' of git://git.kernel...
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=121965ef680000
> kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
> dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12b40c7b680000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10f691ef680000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9e81dc4903c2/disk-13d88ac5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/f40fd7326b3f/vmlinux-13d88ac5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2f399cd6ff7d/bzImage-13d88ac5.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/8e127c645a04/mount_0.gz
>
> The issue was bisected to:
>
> commit f268eedddf3595e85f8883dc50aed29654785696
> Author: Phillip Lougher <phi...@squashfs.org.uk>
> Date: Sat Jun 11 03:21:32 2022 +0000
>
> squashfs: extend "page actor" to handle missing pages

Fixed the issue, and will send a patch shortly.

Phillip

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

fs/squashfs/inode.c:128:60: error: use of undeclared identifier 'sqsh_ino'


Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1566c75b680000

[Edward Adam Davis]

index aa3411354e66..e7c2ccd6a382 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -403,9 +403,11 @@ int squashfs_read_inode(struct inode *inode, long long ino)
} else
squashfs_i(inode)->xattr_count = 0;

+ printk("in: %p, fs: %d, it: %d, %s\n", inode, inode->i_size, type, __func__);
return 0;

failed_read:
+ printk("in: %p, fs: %d, it: %d, %s\n", inode, inode->i_size, type, __func__);
ERROR("Unable to read inode 0x%llx\n", ino);
return err;
}

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=16f91eff680000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=10923b0f680000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 581ce9519339..7db8f2920c9e 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -287,6 +287,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

if (index + 2 > msblk->bytes_used) {
res = -EIO;
+ printk("srd1: i:%d, bu:%d \n", index, msblk->bytes_used);
goto out;
}
res = squashfs_bio_read(sb, index, 2, &bio, &offset);
@@ -295,6 +296,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
res = -EIO;
+ printk("srd2 \n");
goto out_free_bio;
}
/* Extract the length of the metadata block */
@@ -305,6 +307,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
} else {
if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) {
res = -EIO;
+ printk("srd3 \n");
goto out_free_bio;
}
data = bvec_virt(bvec);
@@ -324,6 +327,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
if (length < 0 || length > output->length ||
(index + length) > msblk->bytes_used) {
res = -EIO;
+ printk("srd4: l:%d, ol: %d, bu: %d \n", length, output->length, msblk->bytes_used);
goto out;
}

@@ -336,10 +340,12 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

if (compressed) {
if (!msblk->stream) {
+ printk("srd5 \n");
res = -EIO;
goto out_free_bio;
}
res = msblk->thread_ops->decompress(msblk, bio, offset, length, output);
+ printk("srd6: r: %d \n", res);
} else {
res = copy_bio_to_actor(bio, output, offset, length);

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=12dbf797680000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15986fdf680000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c

index 581ce9519339..1c7c5500206b 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -314,9 +314,11 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
bio_uninit(bio);
kfree(bio);

+ printk("datal: %d \n", length);
compressed = SQUASHFS_COMPRESSED(length);
length = SQUASHFS_COMPRESSED_SIZE(length);
index += 2;
+ printk("datal2: %d, c:%d, i:%d \n", length, compressed, index);

TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
compressed ? "" : "un", length);
@@ -324,6 +326,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

if (length < 0 || length > output->length ||
(index + length) > msblk->bytes_used) {
res = -EIO;

+ printk("srd: l:%d, ol: %d, bu: %d \n", length, output->length, msblk->bytes_used);
goto out;
}

@@ -340,6 +343,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

goto out_free_bio;
}
res = msblk->thread_ops->decompress(msblk, bio, offset, length, output);
+ printk("srd6: r: %d \n", res);
} else {
res = copy_bio_to_actor(bio, output, offset, length);
}

diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c
index 5062326d0efb..dac9eedea868 100644
--- a/fs/squashfs/cache.c
+++ b/fs/squashfs/cache.c
@@ -340,6 +340,7 @@ int squashfs_read_metadata(struct super_block *sb, void *buffer,
if (unlikely(length < 0))
return -EIO;

+ printk("srm: %d\n", length);
while (length) {
entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0);
if (entry->error) {
@@ -381,6 +382,7 @@ struct squashfs_cache_entry *squashfs_get_fragment(struct super_block *sb,
{
struct squashfs_sb_info *msblk = sb->s_fs_info;

+ printk("sgf: %d\n", length);
return squashfs_cache_get(sb, msblk->fragment_cache, start_block,
length);
}
@@ -396,6 +398,7 @@ struct squashfs_cache_entry *squashfs_get_datablock(struct super_block *sb,
{
struct squashfs_sb_info *msblk = sb->s_fs_info;

+ printk("sgd: %d\n", length);
return squashfs_cache_get(sb, msblk->read_page, start_block, length);

index aa3411354e66..f3b0111e6fbd 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -175,6 +175,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
u64 frag_blk;
struct squashfs_lreg_inode *sqsh_ino = &squashfs_ino.lreg;

+ printk("in0: %p, fs: %d, it: %d, %s\n", inode, inode->i_size, type, __func__);
err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
sizeof(*sqsh_ino));
if (err < 0)
@@ -403,6 +404,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=137b0270e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1142f82f680000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c

index 581ce9519339..ba4f53c3725d 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -321,11 +321,16 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
compressed ? "" : "un", length);
}

- if (length < 0 || length > output->length ||
- (index + length) > msblk->bytes_used) {
+
+ if (length < 0) {
res = -EIO;
goto out;
}
+ if (length > output->length || (index + length) > msblk->bytes_used) {
+ printk("srd: l:%d, ol: %d, bu: %d,i:%d, c:%d \n", length,
+ output->length, msblk->bytes_used, index, compressed);
+ length = min_t(int, msblk->bytes_used - index, output->length);
+ }

if (next_index)
*next_index = index + length;

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=16dd2f97680000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1258c947680000

[Edward Adam Davis]

please test squashfs readahead oob

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 13d88ac54ddd

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c

index 581ce9519339..d335f28c822c 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -323,7 +323,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

}
if (length < 0 || length > output->length ||

(index + length) > msblk->bytes_used) {

- res = -EIO;
+ res = length < 0 ? -EIO : -EFBIG;
goto out;
}

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ba8c4c50770..5472ddd3596c 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -461,6 +461,11 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)

TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
page->index, squashfs_i(inode)->start);

+ if (!file_end) {

+ res = -EINVAL;
+ goto out;
+ }
+
if (page->index >= ((i_size_read(inode) + PAGE_SIZE - 1) >>
PAGE_SHIFT))
goto out;

@@ -547,6 +552,9 @@ static void squashfs_readahead(struct readahead_control *ractl)

int i, file_end = i_size_read(inode) >> msblk->block_log;
unsigned int max_pages = 1UL << shift;

+ if (!file_end)
+ return;

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Tested on:

commit: 13d88ac5 Merge tag 'vfs-6.7.fsid' of git://git.kernel...
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=1639ea50e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=beb32a598fd79db9
dashboard link: https://syzkaller.appspot.com/bug?extid=604424eb051c2f696163
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=10560014e80000

[Edward Adam Davis]

[Syz log]

SQUASHFS error: Failed to read block 0x6fc: -5

[Bug]
path_openat() called open_last_lookups() before calling do_open() and
open_last_lookups() will eventually call squashfs_read_inode() to set
inode->i_size, but before setting i_size, it is necessary to obtain file_size
from the disk.

However, during the value retrieval process, the length of the value retrieved
from the disk was greater than output->length, resulting(-EIO) in the failure of
squashfs_read_data(), further leading to i_size has not been initialized,
i.e. its value is 0.

This resulted in the failure of squashfs_read_data(), where "SQUASHFS error:
Failed to read block 0x6fc: -5" was output in the syz log.
This also resulted in the failure of squashfs_cache_get(), outputting "SQUASHFS
error: Unable to read metadata cache entry [6fa]" in the syz log.

[Fix]
Before performing a read ahead operation in squashfs_read_folio() and
squashfs_readahead(), check if i_size is not 0 before continuing.

Optimize the return value of squashfs_read_data() and return -EFBIG when the
length is greater than output->length(or (index + length) >
msblk->bytes_used).

Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com

Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")

Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
fs/squashfs/block.c | 2 +-
fs/squashfs/file.c | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)

--
2.25.1

[Andrew Morton]

On Wed, 15 Nov 2023 12:05:35 +0800 Edward Adam Davis <ead...@qq.com> wrote:

> Before performing a read ahead operation in squashfs_read_folio() and
> squashfs_readahead(), check if i_size is not 0 before continuing.

I'll merge this for testing, pending Phillip's review. One thing:

> --- a/fs/squashfs/block.c
> +++ b/fs/squashfs/block.c
> @@ -323,7 +323,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
> }
> if (length < 0 || length > output->length ||
> (index + length) > msblk->bytes_used) {
> - res = -EIO;
> + res = length < 0 ? -EIO : -EFBIG;
> goto out;
> }

Seems a bit ugly to test `length' twice for the same thing. How about

if (length < 0) {
res = -EIO;

got out;
}
if (length > output->length || (index + length) > msblk->bytes_used) {
res = -EFBIG;
goto out;
}

?

[Phillip Lougher]

> [Bug]
> path_openat() called open_last_lookups() before calling do_open() and
> open_last_lookups() will eventually call squashfs_read_inode() to set
> inode->i_size, but before setting i_size, it is necessary to obtain file_size
> from the disk.
>
> However, during the value retrieval process, the length of the value retrieved
> from the disk was greater than output->length, resulting(-EIO) in the failure of
> squashfs_read_data(), further leading to i_size has not been initialized,
> i.e. its value is 0.
>

NACK

This analysis is completely *wrong*. First, if there was I/O error reading
the inode it would never be created, and squasfs_readahead() would
never be called on it, because it will never exist.

Second i_size isn't unintialised and it isn't 0 in value. Where
you got this bogus information from is because in your test patches,
i.e.

https://lore.kernel.org/all/000000000000bb...@google.com/

You have

+ if (!file_end) {
+ printk("i:%p, is:%d, %s\n", inode, i_size_read(inode), __func__);

+ res = -EINVAL;
+ goto out;
+ }
+

You have used %d, and the result of i_size_read(inode) overflows, giving the
bogus 0 value.

The actual value is 1407374883553280, or 0x5000000000000, which is
too big to fit into an unsigned int.

> This resulted in the failure of squashfs_read_data(), where "SQUASHFS error:
> Failed to read block 0x6fc: -5" was output in the syz log.
> This also resulted in the failure of squashfs_cache_get(), outputting "SQUASHFS
> error: Unable to read metadata cache entry [6fa]" in the syz log.
>

NO, *that* is caused by the failure to read some other inodes which
as a result are correctly not created. Nothing to do with the oops here.

> [Fix]
> Before performing a read ahead operation in squashfs_read_folio() and
> squashfs_readahead(), check if i_size is not 0 before continuing.
>

A third NO, it is only 0 because the variable overflowed.

Additionally, let's look at your "fix" here.

> @@ -461,6 +461,11 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
> TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
> page->index, squashfs_i(inode)->start);
>
> + if (!file_end) {
> + res = -EINVAL;
> + goto out;
> + }
> +

file_end is computed by

int file_end = i_size_read(inode) >> msblk->block_log;

So your "fix" will reject *any* file less than msblk->block_log in
size as invalid, including perfectly valid zero size files (empty
files are valid too).

I already identified the cause and send a fix patch here:

https://lore.kernel.org/all/20231113160901...@squashfs.org.uk/

NACK

Phillip

[Andrew Morton]

On Fri, 17 Nov 2023 14:17:17 +0100 Marek Szyprowski <m.szyp...@samsung.com> wrote:

> > Reported-and-tested-by: syzbot+604424...@syzkaller.appspotmail.com
> > Fixes: f268eedddf35 ("squashfs: extend "page actor" to handle missing pages")
> > Signed-off-by: Edward Adam Davis <ead...@qq.com>
>

> This patch, merged to linux-next as commit 1ff947abe24a ("squashfs: fix
> oob in squashfs_readahead"), breaks mounting squashfs volumes on all my
> test systems. Let me know if you need more information to debug this issue.

Thanks. The patch has been dropped.

[Edward Adam Davis]

On Thu, 16 Nov 2023 15:14:24 +0000, Phillip Lougher wrote:
> > [Bug]
> > path_openat() called open_last_lookups() before calling do_open() and
> > open_last_lookups() will eventually call squashfs_read_inode() to set
> > inode->i_size, but before setting i_size, it is necessary to obtain file_size
> > from the disk.
> >
> > However, during the value retrieval process, the length of the value retrieved
> > from the disk was greater than output->length, resulting(-EIO) in the failure of
> > squashfs_read_data(), further leading to i_size has not been initialized,
> > i.e. its value is 0.
> >
>
> NACK
>
> This analysis is completely *wrong*. First, if there was I/O error reading
> the inode it would never be created, and squasfs_readahead() would
> never be called on it, because it will never exist.
>
> Second i_size isn't unintialised and it isn't 0 in value. Where
> you got this bogus information from is because in your test patches,
> i.e.

[There is my debuging patch]
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 581ce9519339..1c7c5500206b 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c

@@ -314,9 +314,11 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
bio_uninit(bio);
kfree(bio);

+ printk("datal: %d \n", length);
compressed = SQUASHFS_COMPRESSED(length);
length = SQUASHFS_COMPRESSED_SIZE(length);
index += 2;
+ printk("datal2: %d, c:%d, i:%d \n", length, compressed, index);

TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
compressed ? "" : "un", length);

@@ -324,6 +326,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,

if (length < 0 || length > output->length ||
(index + length) > msblk->bytes_used) {

res = -EIO;
+ printk("srd: l:%d, ol: %d, bu: %d \n", length, output->length, msblk->bytes_used);
goto out;
}

patch link: https://syzkaller.appspot.com/text?tag=Patch&x=1142f82f680000

[There is my test log]
[ 457.030754][ T8879] datal: 65473
[ 457.034334][ T8879] datal2: 32705, c:0, i:1788
[ 457.039253][ T8879] srd: l:32705, ol: 8192, bu: 1870
[ 457.044513][ T8879] SQUASHFS error: Failed to read block 0x6fc: -5
[ 457.052034][ T8879] SQUASHFS error: Unable to read metadata cache entry [6fa]
log link: https://syzkaller.appspot.com/x/log.txt?x=137b0270e80000

[Answer your doubts]
Based on the above test, it can be clearly determined that length=32705 is
greater than the maximum metadata size of 8192, resulting in squashfs_read_data() failed.
This will further lead to squashfs_cache_get() returns "entry->error=entry->length=-EIO",
followed by squashfs_read_metadata() failed, which will ultimately result in i_size not
being initialized in squashfs_read_inode().

The following are the relevant call stacks:
23 const struct inode_operations squashfs_dir_inode_ops = {
24 .lookup = squashfs_lookup,
25 .listxattr = squashfs_listxattr
26 };
NORMAL +0 ~0 -0 fs/squashfs/namei.c

path_openat()->open_last_lookups()->lookup_open()
1 if (d_in_lookup(dentry)) {
3455 struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 1 nd->flags);

squashfs_lookup()->
squashfs_iget()->
squashfs_read_inode()->
init inode->i_size, example: inode->i_size = sqsh_ino->file_size;

edward

[Marek Szyprowski]

Hi All,

This patch, merged to linux-next as commit 1ff947abe24a ("squashfs: fix
oob in squashfs_readahead"), breaks mounting squashfs volumes on all my
test systems. Let me know if you need more information to debug this issue.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland