[syzbot] [ext4?] KASAN: slab-use-after-free Read in ext4_convert_inline_data_nolock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 17214b70a159 Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1123dba6c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d40f6d44826f6cf7
dashboard link: https://syzkaller.appspot.com/bug?extid=db6caad9ebd2c8022b41
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d166fda7fbbd/disk-17214b70.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0c16461022b9/vmlinux-17214b70.xz
kernel image: https://storage.googleapis.com/syzbot-assets/53e9e40da8bb/bzImage-17214b70.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+db6caa...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in ext4_read_inline_data fs/ext4/inline.c:199 [inline]
BUG: KASAN: slab-use-after-free in ext4_convert_inline_data_nolock+0x31a/0xd80 fs/ext4/inline.c:1204
Read of size 20 at addr ffff888023fbe1a3 by task syz-executor.0/14243

CPU: 1 PID: 14243 Comm: syz-executor.0 Not tainted 6.3.0-rc3-syzkaller-00012-g17214b70a159 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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:319 [inline]
print_report+0x163/0x540 mm/kasan/report.c:430
kasan_report+0x176/0x1b0 mm/kasan/report.c:536
kasan_check_range+0x283/0x290 mm/kasan/generic.c:187
__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
ext4_read_inline_data fs/ext4/inline.c:199 [inline]
ext4_convert_inline_data_nolock+0x31a/0xd80 fs/ext4/inline.c:1204
ext4_convert_inline_data+0x4da/0x620 fs/ext4/inline.c:2065
ext4_fallocate+0x14d/0x2050 fs/ext4/extents.c:4701
vfs_fallocate+0x54b/0x6b0 fs/open.c:324
ksys_fallocate fs/open.c:347 [inline]
__do_sys_fallocate fs/open.c:355 [inline]
__se_sys_fallocate fs/open.c:353 [inline]
__x64_sys_fallocate+0xbd/0x100 fs/open.c:353
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f01bac8c0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007f01bba76168 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f01badac050 RCX: 00007f01bac8c0f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f01bace7b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000008000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc150e1a5f R14: 00007f01bba76300 R15: 0000000000022000
</TASK>

Allocated by task 4435:
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:196 [inline]
__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc+0xb9/0x230 mm/slab_common.c:980
kmalloc include/linux/slab.h:584 [inline]
tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x254/0x4e0 security/tomoyo/file.c:771
security_file_open+0x63/0xa0 security/security.c:1719
do_dentry_open+0x308/0x10f0 fs/open.c:907
do_open fs/namei.c:3560 [inline]
path_openat+0x27b3/0x3170 fs/namei.c:3715
do_filp_open+0x234/0x490 fs/namei.c:3742
do_sys_openat2+0x13f/0x500 fs/open.c:1348
do_sys_open fs/open.c:1364 [inline]
__do_sys_openat fs/open.c:1380 [inline]
__se_sys_openat fs/open.c:1375 [inline]
__x64_sys_openat+0x247/0x290 fs/open.c:1375
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 4435:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:162 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook mm/slub.c:1807 [inline]
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0x264/0x3c0 mm/slub.c:3800
tomoyo_realpath_from_path+0x5a3/0x5e0 security/tomoyo/realpath.c:286
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x254/0x4e0 security/tomoyo/file.c:771
security_file_open+0x63/0xa0 security/security.c:1719
do_dentry_open+0x308/0x10f0 fs/open.c:907
do_open fs/namei.c:3560 [inline]
path_openat+0x27b3/0x3170 fs/namei.c:3715
do_filp_open+0x234/0x490 fs/namei.c:3742
do_sys_openat2+0x13f/0x500 fs/open.c:1348
do_sys_open fs/open.c:1364 [inline]
__do_sys_openat fs/open.c:1380 [inline]
__se_sys_openat fs/open.c:1375 [inline]
__x64_sys_openat+0x247/0x290 fs/open.c:1375
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888023fbe000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 419 bytes inside of
freed 4096-byte region [ffff888023fbe000, ffff888023fbf000)

The buggy address belongs to the physical page:
page:ffffea00008fee00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23fb8
head:ffffea00008fee00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012442140 ffffea0000835200 dead000000000002
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 6719, tgid 6717 (syz-executor.3), ts 223345556670, free_ts 223329495124
prep_new_page mm/page_alloc.c:2552 [inline]
get_page_from_freelist+0x3246/0x33c0 mm/page_alloc.c:4325
__alloc_pages+0x255/0x670 mm/page_alloc.c:5591
alloc_slab_page+0x6a/0x160 mm/slub.c:1851
allocate_slab mm/slub.c:1998 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2051
___slab_alloc+0xa85/0x10a0 mm/slub.c:3193
__slab_alloc mm/slub.c:3292 [inline]
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3491
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1061
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
alloc_super+0x59/0x930 fs/super.c:202
sget_fc+0x222/0x630 fs/super.c:581
get_tree_bdev+0x26f/0x620 fs/super.c:1271
vfs_get_tree+0x8c/0x270 fs/super.c:1510
do_new_mount+0x28f/0xae0 fs/namespace.c:3042
do_mount fs/namespace.c:3385 [inline]
__do_sys_mount fs/namespace.c:3594 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3571
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1453 [inline]
free_pcp_prepare mm/page_alloc.c:1503 [inline]
free_unref_page_prepare+0xe2f/0xe70 mm/page_alloc.c:3387
free_unref_page+0x37/0x3f0 mm/page_alloc.c:3482
discard_slab mm/slub.c:2098 [inline]
__unfreeze_partials+0x1b1/0x1f0 mm/slub.c:2637
put_cpu_partial+0x116/0x180 mm/slub.c:2713
qlist_free_all+0x22/0x60 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:186 [inline]
slab_post_alloc_hook+0x68/0x3a0 mm/slab.h:769
slab_alloc_node mm/slub.c:3452 [inline]
slab_alloc mm/slub.c:3460 [inline]
__kmem_cache_alloc_lru mm/slub.c:3467 [inline]
kmem_cache_alloc+0x11f/0x2e0 mm/slub.c:3476
getname_flags+0xbc/0x4e0 fs/namei.c:140
getname fs/namei.c:219 [inline]
__do_sys_symlink fs/namei.c:4445 [inline]
__se_sys_symlink fs/namei.c:4443 [inline]
__x64_sys_symlink+0x5f/0x90 fs/namei.c:4443
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff888023fbe080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888023fbe100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888023fbe180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888023fbe200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888023fbe280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1034aed5c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=9c35b3803e5ad668

dashboard link: https://syzkaller.appspot.com/bug?extid=db6caad9ebd2c8022b41
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a2cd05c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=158e1f29c80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/65fe3e7679b9/disk-3a93e403.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/169220ad146c/vmlinux-3a93e403.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f5e2d192c51/bzImage-3a93e403.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/343663881b01/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+db6caa...@syzkaller.appspotmail.com

EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_read_inline_data fs/ext4/inline.c:199 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_convert_inline_data_nolock+0x31a/0xd80 fs/ext4/inline.c:1204
Read of size 20 at addr ffff88807645e1a3 by task syz-executor378/5075

CPU: 0 PID: 5075 Comm: syz-executor378 Not tainted 6.3.0-rc4-syzkaller-00025-g3a93e40326c8 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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:319 [inline]
print_report+0x163/0x540 mm/kasan/report.c:430
kasan_report+0x176/0x1b0 mm/kasan/report.c:536
kasan_check_range+0x283/0x290 mm/kasan/generic.c:187
__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
ext4_read_inline_data fs/ext4/inline.c:199 [inline]
ext4_convert_inline_data_nolock+0x31a/0xd80 fs/ext4/inline.c:1204
ext4_convert_inline_data+0x4da/0x620 fs/ext4/inline.c:2065
ext4_fallocate+0x14d/0x2050 fs/ext4/extents.c:4701
vfs_fallocate+0x54b/0x6b0 fs/open.c:324
ksys_fallocate fs/open.c:347 [inline]
__do_sys_fallocate fs/open.c:355 [inline]
__se_sys_fallocate fs/open.c:353 [inline]
__x64_sys_fallocate+0xbd/0x100 fs/open.c:353
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

RIP: 0033:0x7fb0579425c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 18 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdcef99758 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb0579425c9

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004

RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000003
R10: 0000000000008000 R11: 0000000000000246 R12: 00007ffdcef99790
R13: 00007ffdcef99788 R14: 00007ffdcef99784 R15: 0000000000000003
</TASK>

Allocated by task 5023:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52

__kasan_slab_alloc+0x66/0x70 mm/kasan/common.c:328

kasan_slab_alloc include/linux/kasan.h:186 [inline]
slab_post_alloc_hook+0x68/0x3a0 mm/slab.h:769
slab_alloc_node mm/slub.c:3452 [inline]
slab_alloc mm/slub.c:3460 [inline]
__kmem_cache_alloc_lru mm/slub.c:3467 [inline]
kmem_cache_alloc+0x11f/0x2e0 mm/slub.c:3476

mt_alloc_one lib/maple_tree.c:159 [inline]
mas_alloc_nodes+0x26e/0x780 lib/maple_tree.c:1233
mas_node_count_gfp lib/maple_tree.c:1318 [inline]
mas_preallocate+0x131/0x350 lib/maple_tree.c:5717
vma_iter_prealloc mm/internal.h:972 [inline]
__split_vma+0x1e0/0x7f0 mm/mmap.c:2177
mprotect_fixup+0x5f5/0x920 mm/mprotect.c:663
do_mprotect_pkey+0x8f8/0xc60 mm/mprotect.c:831
__do_sys_mprotect mm/mprotect.c:852 [inline]
__se_sys_mprotect mm/mprotect.c:849 [inline]
__x64_sys_mprotect+0x80/0x90 mm/mprotect.c:849

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5023:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:162 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook mm/slub.c:1807 [inline]
slab_free mm/slub.c:3787 [inline]

kmem_cache_free+0x297/0x520 mm/slub.c:3809
mas_destroy+0x1bdc/0x2280 lib/maple_tree.c:5774
mas_store_prealloc+0x351/0x460 lib/maple_tree.c:5702
vma_complete+0x1ed/0x970 mm/mmap.c:572
__split_vma+0x7b9/0x7f0 mm/mmap.c:2214
mprotect_fixup+0x5f5/0x920 mm/mprotect.c:663
do_mprotect_pkey+0x8f8/0xc60 mm/mprotect.c:831
__do_sys_mprotect mm/mprotect.c:852 [inline]
__se_sys_mprotect mm/mprotect.c:849 [inline]
__x64_sys_mprotect+0x80/0x90 mm/mprotect.c:849

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88807645e000
which belongs to the cache maple_node of size 256
The buggy address is located 163 bytes to the right of
allocated 256-byte region [ffff88807645e000, ffff88807645e100)

The buggy address belongs to the physical page:

page:ffffea0001d91780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7645e
head:ffffea0001d91780 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0

flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000010200 ffff8880124cd000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000

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

page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5023, tgid 5023 (rm), ts 57145564531, free_ts 41308598324
prep_new_page mm/page_alloc.c:2553 [inline]
get_page_from_freelist+0x3246/0x33c0 mm/page_alloc.c:4326
__alloc_pages+0x255/0x670 mm/page_alloc.c:5592

alloc_slab_page+0x6a/0x160 mm/slub.c:1851
allocate_slab mm/slub.c:1998 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2051
___slab_alloc+0xa85/0x10a0 mm/slub.c:3193
__slab_alloc mm/slub.c:3292 [inline]
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]

slab_alloc mm/slub.c:3460 [inline]
__kmem_cache_alloc_lru mm/slub.c:3467 [inline]

kmem_cache_alloc+0x1b9/0x2e0 mm/slub.c:3476
mt_alloc_one lib/maple_tree.c:159 [inline]
mas_alloc_nodes+0x26e/0x780 lib/maple_tree.c:1233
mas_node_count_gfp lib/maple_tree.c:1318 [inline]
mas_preallocate+0x131/0x350 lib/maple_tree.c:5717
vma_iter_prealloc mm/internal.h:972 [inline]
__split_vma+0x1e0/0x7f0 mm/mmap.c:2177
mprotect_fixup+0x5f5/0x920 mm/mprotect.c:663
do_mprotect_pkey+0x8f8/0xc60 mm/mprotect.c:831
__do_sys_mprotect mm/mprotect.c:852 [inline]
__se_sys_mprotect mm/mprotect.c:849 [inline]
__x64_sys_mprotect+0x80/0x90 mm/mprotect.c:849

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]

free_pages_prepare mm/page_alloc.c:1454 [inline]
free_pcp_prepare mm/page_alloc.c:1504 [inline]
free_unref_page_prepare+0xe2f/0xe70 mm/page_alloc.c:3388
free_unref_page+0x37/0x3f0 mm/page_alloc.c:3483

discard_slab mm/slub.c:2098 [inline]
__unfreeze_partials+0x1b1/0x1f0 mm/slub.c:2637
put_cpu_partial+0x116/0x180 mm/slub.c:2713
qlist_free_all+0x22/0x60 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:186 [inline]
slab_post_alloc_hook+0x68/0x3a0 mm/slab.h:769
slab_alloc_node mm/slub.c:3452 [inline]
slab_alloc mm/slub.c:3460 [inline]
__kmem_cache_alloc_lru mm/slub.c:3467 [inline]
kmem_cache_alloc+0x11f/0x2e0 mm/slub.c:3476

vm_area_alloc+0x24/0xe0 kernel/fork.c:458
mmap_region+0xbfb/0x20c0 mm/mmap.c:2553
do_mmap+0x8c9/0xf70 mm/mmap.c:1364
vm_mmap_pgoff+0x1ce/0x2e0 mm/util.c:542
ksys_mmap_pgoff+0x4f9/0x6d0 mm/mmap.c:1410

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:

ffff88807645e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807645e100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807645e180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88807645e200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807645e280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[syzbot]

syzbot suspects this issue was fixed by commit:

commit 6f861765464f43a71462d52026fbddfc858239a5
Author: Jan Kara <ja...@suse.cz>
Date: Wed Nov 1 17:43:10 2023 +0000

fs: Block writes to mounted block devices

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1606d4ffe80000
start commit: 3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=9c35b3803e5ad668
dashboard link: https://syzkaller.appspot.com/bug?extid=db6caad9ebd2c8022b41

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a2cd05c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=158e1f29c80000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: fs: Block writes to mounted block devices

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Jan Kara]

On Thu 01-02-24 00:20:04, syzbot wrote:
> syzbot suspects this issue was fixed by commit:
>
> commit 6f861765464f43a71462d52026fbddfc858239a5
> Author: Jan Kara <ja...@suse.cz>
> Date: Wed Nov 1 17:43:10 2023 +0000
>
> fs: Block writes to mounted block devices
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1606d4ffe80000
> start commit: 3a93e40326c8 Merge tag 'for-linus' of git://git.kernel.org..
> git tree: upstream
> kernel config: https://syzkaller.appspot.com/x/.config?x=9c35b3803e5ad668
> dashboard link: https://syzkaller.appspot.com/bug?extid=db6caad9ebd2c8022b41
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a2cd05c80000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=158e1f29c80000
>
> If the result looks correct, please mark the issue as fixed by replying with:

Yep, the reproducer seems to mess with the loop device itself.

#syz fix: fs: Block writes to mounted block devices

Honza
--
Jan Kara <ja...@suse.com>
SUSE Labs, CR