[syzbot] [nilfs?] KASAN: slab-use-after-free Read in nilfs_load_inode_block (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fdf0eaf11452 Linux 6.5-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11354edca80000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4507c291b5ab5d4
dashboard link: https://syzkaller.appspot.com/bug?extid=74db8b3087f293d3a13a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/227b5c9aa7b3/disk-fdf0eaf1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aedc7f03bef6/vmlinux-fdf0eaf1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec543f1fd878/bzImage-fdf0eaf1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+74db8b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in nilfs_load_inode_block+0x11e/0x280 fs/nilfs2/inode.c:1030
Read of size 8 at addr ffff888023e50230 by task syz-executor.2/5056

CPU: 1 PID: 5056 Comm: syz-executor.2 Not tainted 6.5.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
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+0x175/0x1b0 mm/kasan/report.c:588
nilfs_load_inode_block+0x11e/0x280 fs/nilfs2/inode.c:1030
__nilfs_mark_inode_dirty+0xa5/0x280 fs/nilfs2/inode.c:1107
nilfs_dirty_inode+0x164/0x200 fs/nilfs2/inode.c:1148
__mark_inode_dirty+0x305/0xd90 fs/fs-writeback.c:2430
mark_inode_dirty_sync include/linux/fs.h:2153 [inline]
iput+0x1f2/0x8f0 fs/inode.c:1814
nilfs_dispose_list+0x51d/0x5c0 fs/nilfs2/segment.c:816
nilfs_detach_log_writer+0xaf1/0xbb0 fs/nilfs2/segment.c:2859
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:498
generic_shutdown_super+0x134/0x340 fs/super.c:499
kill_block_super+0x68/0xa0 fs/super.c:1417
deactivate_locked_super+0xa4/0x110 fs/super.c:330
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1254
task_work_run+0x24a/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f723027de57
Code: b0 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b0 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe73394f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f723027de57
RDX: 0000000000000000 RSI: 000000000000000a RDI: 00007ffe73395010
RBP: 00007ffe73395010 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffe733960d0
R13: 00007f72302c73b9 R14: 0000000000032737 R15: 000000000000000c
</TASK>

Allocated by task 5412:
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
kmalloc include/linux/slab.h:582 [inline]
kzalloc include/linux/slab.h:703 [inline]
nilfs_find_or_create_root+0x137/0x4e0 fs/nilfs2/the_nilfs.c:851
nilfs_attach_checkpoint+0x123/0x4d0 fs/nilfs2/super.c:550
nilfs_fill_super+0x321/0x600 fs/nilfs2/super.c:1095
nilfs_mount+0x637/0x950 fs/nilfs2/super.c:1343
legacy_get_tree+0xef/0x190 fs/fs_context.c:611
vfs_get_tree+0x8c/0x270 fs/super.c:1519
do_new_mount+0x28f/0xae0 fs/namespace.c:3335
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
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 5056:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
____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:1792 [inline]
slab_free_freelist_hook mm/slub.c:1818 [inline]
slab_free mm/slub.c:3801 [inline]
__kmem_cache_free+0x25f/0x3b0 mm/slub.c:3814
nilfs_segctor_destroy fs/nilfs2/segment.c:2782 [inline]
nilfs_detach_log_writer+0x8c1/0xbb0 fs/nilfs2/segment.c:2845
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:498
generic_shutdown_super+0x134/0x340 fs/super.c:499
kill_block_super+0x68/0xa0 fs/super.c:1417
deactivate_locked_super+0xa4/0x110 fs/super.c:330
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1254
task_work_run+0x24a/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888023e50200
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
freed 256-byte region [ffff888023e50200, ffff888023e50300)

The buggy address belongs to the physical page:
page:ffffea00008f9400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23e50
head:ffffea00008f9400 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012841b40 dead000000000100 dead000000000122
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 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5181, tgid 5181 (syz-executor.2), ts 197741582486, free_ts 196828318372
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
prep_new_page mm/page_alloc.c:1577 [inline]
get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
__alloc_pages+0x255/0x670 mm/page_alloc.c:4477
alloc_slab_page+0x6a/0x160 mm/slub.c:1862
allocate_slab mm/slub.c:2009 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2062
___slab_alloc+0xade/0x1100 mm/slub.c:3215
__slab_alloc mm/slub.c:3314 [inline]
__slab_alloc_node mm/slub.c:3367 [inline]
slab_alloc_node mm/slub.c:3460 [inline]
__kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3509
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1076
kmalloc include/linux/slab.h:582 [inline]
kzalloc include/linux/slab.h:703 [inline]
smk_fetch+0x92/0x140 security/smack/smack_lsm.c:291
smack_d_instantiate+0x868/0xb40 security/smack/smack_lsm.c:3541
security_d_instantiate+0x9b/0xf0 security/security.c:3760
d_instantiate_new+0x65/0x120 fs/dcache.c:2053
ext4_add_nondir+0x22d/0x290 fs/ext4/namei.c:2797
ext4_symlink+0x908/0xb30 fs/ext4/namei.c:3431
vfs_symlink+0x12f/0x2a0 fs/namei.c:4477
do_symlinkat+0x201/0x610 fs/namei.c:4503
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1161 [inline]
free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2443
discard_slab mm/slub.c:2108 [inline]
__unfreeze_partials+0x1dc/0x220 mm/slub.c:2647
put_cpu_partial+0x116/0x180 mm/slub.c:2723
__slab_free+0x2b6/0x390 mm/slub.c:3671
qlist_free_all+0x22/0x60 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:186 [inline]
slab_post_alloc_hook+0x6c/0x3b0 mm/slab.h:762
slab_alloc_node mm/slub.c:3470 [inline]
__kmem_cache_alloc_node+0x141/0x270 mm/slub.c:3509
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1076
kmalloc include/linux/slab.h:582 [inline]
kzalloc include/linux/slab.h:703 [inline]
mca_alloc net/ipv6/mcast.c:880 [inline]
__ipv6_dev_mc_inc+0x426/0xa80 net/ipv6/mcast.c:936
addrconf_join_solict net/ipv6/addrconf.c:2179 [inline]
addrconf_dad_begin net/ipv6/addrconf.c:3995 [inline]
addrconf_dad_work+0x424/0x16b0 net/ipv6/addrconf.c:4120
process_one_work+0x92c/0x12c0 kernel/workqueue.c:2597
worker_thread+0xa63/0x1210 kernel/workqueue.c:2748
kthread+0x2b8/0x350 kernel/kthread.c:389

Memory state around the buggy address:
ffff888023e50100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888023e50180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888023e50200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888023e50280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888023e50300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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If the bug is already fixed, let syzbot know by replying with:
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 5f0bc0b042fc mm: suppress mm fault logging if fatal signal..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1382e2f9a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=5d10d93e1ae1f229

dashboard link: https://syzkaller.appspot.com/bug?extid=74db8b3087f293d3a13a
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=15176d81a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132d93d9a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b15763fff0b8/disk-5f0bc0b0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d0b1ccb084b3/vmlinux-5f0bc0b0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a5a2e6f8db73/bzImage-5f0bc0b0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/0fd90c1b386c/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+74db8b...@syzkaller.appspotmail.com

NILFS (loop4): discard dirty block: blocknr=25, size=4096
NILFS (loop4): disposed unprocessed dirty file(s) when detaching log writer

==================================================================
BUG: KASAN: slab-use-after-free in nilfs_load_inode_block+0x11e/0x280 fs/nilfs2/inode.c:1030

Read of size 8 at addr ffff88802ba11030 by task syz-executor459/5018

CPU: 0 PID: 5018 Comm: syz-executor459 Not tainted 6.5.0-rc3-syzkaller-00025-g5f0bc0b042fc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023

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+0x175/0x1b0 mm/kasan/report.c:588
nilfs_load_inode_block+0x11e/0x280 fs/nilfs2/inode.c:1030
__nilfs_mark_inode_dirty+0xa5/0x280 fs/nilfs2/inode.c:1107
nilfs_dirty_inode+0x164/0x200 fs/nilfs2/inode.c:1148
__mark_inode_dirty+0x305/0xd90 fs/fs-writeback.c:2430
mark_inode_dirty_sync include/linux/fs.h:2153 [inline]
iput+0x1f2/0x8f0 fs/inode.c:1814
nilfs_dispose_list+0x51d/0x5c0 fs/nilfs2/segment.c:816
nilfs_detach_log_writer+0xaf1/0xbb0 fs/nilfs2/segment.c:2859
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:498
generic_shutdown_super+0x134/0x340 fs/super.c:499
kill_block_super+0x68/0xa0 fs/super.c:1417
deactivate_locked_super+0xa4/0x110 fs/super.c:330
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1254
task_work_run+0x24a/0x300 kernel/task_work.c:179

ptrace_notify+0x2cd/0x380 kernel/signal.c:2376
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:252 [inline]
syscall_exit_to_user_mode_prepare kernel/entry/common.c:279 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:284 [inline]
syscall_exit_to_user_mode+0x157/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fa78ff75ee7
Code: 08 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b0 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe7acb7da8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fa78ff75ee7
RDX: 0000000000000000 RSI: 000000000000000a RDI: 00007ffe7acb7e60
RBP: 00007ffe7acb7e60 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000202 R12: 00007ffe7acb8f20
R13: 00005555556ce700 R14: 431bde82d7b634db R15: 00007ffe7acb8ec4
</TASK>

Allocated by task 7068:

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
kmalloc include/linux/slab.h:582 [inline]
kzalloc include/linux/slab.h:703 [inline]
nilfs_find_or_create_root+0x137/0x4e0 fs/nilfs2/the_nilfs.c:851
nilfs_attach_checkpoint+0x123/0x4d0 fs/nilfs2/super.c:550
nilfs_fill_super+0x321/0x600 fs/nilfs2/super.c:1095
nilfs_mount+0x637/0x950 fs/nilfs2/super.c:1343
legacy_get_tree+0xef/0x190 fs/fs_context.c:611
vfs_get_tree+0x8c/0x270 fs/super.c:1519
do_new_mount+0x28f/0xae0 fs/namespace.c:3335
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
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 5018:

kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
____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:1792 [inline]
slab_free_freelist_hook mm/slub.c:1818 [inline]
slab_free mm/slub.c:3801 [inline]
__kmem_cache_free+0x25f/0x3b0 mm/slub.c:3814
nilfs_segctor_destroy fs/nilfs2/segment.c:2782 [inline]
nilfs_detach_log_writer+0x8c1/0xbb0 fs/nilfs2/segment.c:2845
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:498
generic_shutdown_super+0x134/0x340 fs/super.c:499
kill_block_super+0x68/0xa0 fs/super.c:1417
deactivate_locked_super+0xa4/0x110 fs/super.c:330
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1254
task_work_run+0x24a/0x300 kernel/task_work.c:179

ptrace_notify+0x2cd/0x380 kernel/signal.c:2376
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:252 [inline]
syscall_exit_to_user_mode_prepare kernel/entry/common.c:279 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:284 [inline]
syscall_exit_to_user_mode+0x157/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88802ba11000

which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of

freed 256-byte region [ffff88802ba11000, ffff88802ba11100)

The buggy address belongs to the physical page:

page:ffffea0000ae8400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ba10
head:ffffea0000ae8400 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0

flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012841b40 dead000000000100 dead000000000122
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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (init), ts 16455889560, free_ts 12781023907

set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
prep_new_page mm/page_alloc.c:1577 [inline]
get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
__alloc_pages+0x255/0x670 mm/page_alloc.c:4477
alloc_slab_page+0x6a/0x160 mm/slub.c:1862
allocate_slab mm/slub.c:2009 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2062
___slab_alloc+0xade/0x1100 mm/slub.c:3215
__slab_alloc mm/slub.c:3314 [inline]
__slab_alloc_node mm/slub.c:3367 [inline]
slab_alloc_node mm/slub.c:3460 [inline]
__kmem_cache_alloc_node+0x1af/0x270 mm/slub.c:3509
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1076
kmalloc include/linux/slab.h:582 [inline]
kzalloc include/linux/slab.h:703 [inline]
smk_fetch+0x92/0x140 security/smack/smack_lsm.c:291

smack_d_instantiate+0x8d7/0xb40 security/smack/smack_lsm.c:3547
security_d_instantiate+0x9b/0xf0 security/security.c:3760
d_splice_alias+0x6f/0x330 fs/dcache.c:3146
ext4_lookup+0x284/0x750 fs/ext4/namei.c:1879
__lookup_slow+0x282/0x3e0 fs/namei.c:1690
lookup_slow+0x53/0x70 fs/namei.c:1707
walk_component fs/namei.c:1998 [inline]
link_path_walk+0x9c8/0xe70 fs/namei.c:2325

page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1161 [inline]
free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2443

vfree+0x186/0x2e0 mm/vmalloc.c:2842
delayed_vfree_work+0x56/0x80 mm/vmalloc.c:2763

process_one_work+0x92c/0x12c0 kernel/workqueue.c:2597
worker_thread+0xa63/0x1210 kernel/workqueue.c:2748
kthread+0x2b8/0x350 kernel/kthread.c:389

ret_from_fork+0x2e/0x60 arch/x86/kernel/process.c:145
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:296

Memory state around the buggy address:

ffff88802ba10f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802ba10f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802ba11000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802ba11080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802ba11100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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.

[syzbot]

syzbot has bisected this issue to:

commit 28a65b49eb53e172d23567005465019658bfdb4d
Author: Ryusuke Konishi <konishi...@gmail.com>
Date: Thu Apr 27 01:15:26 2023 +0000

nilfs2: do not write dirty data after degenerating to read-only

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=177150e5a80000
start commit: 5f0bc0b042fc mm: suppress mm fault logging if fatal signal..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=14f150e5a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=10f150e5a80000

kernel config: https://syzkaller.appspot.com/x/.config?x=5d10d93e1ae1f229
dashboard link: https://syzkaller.appspot.com/bug?extid=74db8b3087f293d3a13a

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15176d81a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132d93d9a80000

Reported-by: syzbot+74db8b...@syzkaller.appspotmail.com
Fixes: 28a65b49eb53 ("nilfs2: do not write dirty data after degenerating to read-only")

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

[Ryusuke Konishi]

During unmount process of nilfs2, nothing holds nilfs_root structure after
nilfs2 detaches its writer in nilfs_detach_log_writer(). Previously,
nilfs_evict_inode() could cause use-after-free read for nilfs_root if
inodes are left in "garbage_list" and released by nilfs_dispose_list at
the end of nilfs_detach_log_writer(), and this bug was fixed by
commit 9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root in
nilfs_evict_inode()").

However, it turned out that there is another possibility of UAF in the
call path where mark_inode_dirty_sync() is called from iput():

nilfs_detach_log_writer()
nilfs_dispose_list()
iput()
mark_inode_dirty_sync()
__mark_inode_dirty()
nilfs_dirty_inode()
__nilfs_mark_inode_dirty()
nilfs_load_inode_block() --> causes UAF of nilfs_root struct

This can happen after commit 0ae45f63d4ef ("vfs: add support for a
lazytime mount option"), which changed iput() to call
mark_inode_dirty_sync() on its final reference if i_state has I_DIRTY_TIME
flag and i_nlink is non-zero.

This issue appears after commit 28a65b49eb53 ("nilfs2: do not write dirty
data after degenerating to read-only") when using the syzbot reproducer,
but the issue has potentially existed before.

Fix this issue by adding a "purging flag" to the nilfs structure, setting
that flag while disposing the "garbage_list" and checking it in
__nilfs_mark_inode_dirty().

Unlike commit 9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root
in nilfs_evict_inode()"), this patch does not rely on ns_writer to
determine whether to skip operations, so as not to break recovery on
mount. The nilfs_salvage_orphan_logs routine dirties the buffer of
salvaged data before attaching the log writer, so changing
__nilfs_mark_inode_dirty() to skip the operation when ns_writer is NULL
will cause recovery write to fail. The purpose of using the cleanup-only
flag is to allow for narrowing of such conditions.

Signed-off-by: Ryusuke Konishi <konishi...@gmail.com>
Reported-by: syzbot+74db8b...@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/000000000000b4...@google.com
Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
Tested-by: Ryusuke Konishi <konishi...@gmail.com>
Cc: <sta...@vger.kernel.org> # 4.0+
---
fs/nilfs2/inode.c | 8 ++++++++
fs/nilfs2/segment.c | 2 ++
fs/nilfs2/the_nilfs.h | 2 ++
3 files changed, 12 insertions(+)

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index a8ce522ac747..35bc79305318 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -1101,9 +1101,17 @@ int nilfs_set_file_dirty(struct inode *inode, unsigned int nr_dirty)

int __nilfs_mark_inode_dirty(struct inode *inode, int flags)
{
+ struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
struct buffer_head *ibh;
int err;

+ /*
+ * Do not dirty inodes after the log writer has been detached
+ * and its nilfs_root struct has been freed.
+ */
+ if (unlikely(nilfs_purging(nilfs)))
+ return 0;
+
err = nilfs_load_inode_block(inode, &ibh);
if (unlikely(err)) {
nilfs_warn(inode->i_sb,
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index c2553024bd25..581691e4be49 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2845,6 +2845,7 @@ void nilfs_detach_log_writer(struct super_block *sb)
nilfs_segctor_destroy(nilfs->ns_writer);
nilfs->ns_writer = NULL;
}
+ set_nilfs_purging(nilfs);

/* Force to free the list of dirty files */
spin_lock(&nilfs->ns_inode_lock);
@@ -2857,4 +2858,5 @@ void nilfs_detach_log_writer(struct super_block *sb)
up_write(&nilfs->ns_segctor_sem);

nilfs_dispose_list(nilfs, &garbage_list, 1);
+ clear_nilfs_purging(nilfs);
}
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 47c7dfbb7ea5..cd4ae1b8ae16 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -29,6 +29,7 @@ enum {
THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
THE_NILFS_GC_RUNNING, /* gc process is running */
THE_NILFS_SB_DIRTY, /* super block is dirty */
+ THE_NILFS_PURGING, /* disposing dirty files for cleanup */
};

/**
@@ -208,6 +209,7 @@ THE_NILFS_FNS(INIT, init)
THE_NILFS_FNS(DISCONTINUED, discontinued)
THE_NILFS_FNS(GC_RUNNING, gc_running)
THE_NILFS_FNS(SB_DIRTY, sb_dirty)
+THE_NILFS_FNS(PURGING, purging)

/*
* Mount option operations
--
2.34.1