[v5.15] KASAN: null-ptr-deref Read in __wait_on_buffer

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 43bb85222e53 Linux 5.15.193
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17ea3b62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=e72c01cff764acdfa94a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/aa8fda38f146/disk-43bb8522.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5cfcd43783fc/vmlinux-43bb8522.xz
kernel image: https://storage.googleapis.com/syzbot-assets/582ede77e278/bzImage-43bb8522.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e72c01...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
BUG: KASAN: null-ptr-deref in wait_on_bit_io include/linux/wait_bit.h:99 [inline]
BUG: KASAN: null-ptr-deref in __wait_on_buffer+0x30/0x90 fs/buffer.c:122
Read of size 8 at addr 0000000000000000 by task syz.0.12/4343

CPU: 1 PID: 4343 Comm: syz.0.12 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
__kasan_report mm/kasan/report.c:438 [inline]
kasan_report+0xd5/0x130 mm/kasan/report.c:451
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:71 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
wait_on_bit_io include/linux/wait_bit.h:99 [inline]
__wait_on_buffer+0x30/0x90 fs/buffer.c:122
flush_commit_list+0xf3c/0x1d70 fs/reiserfs/journal.c:1069
flush_older_commits fs/reiserfs/journal.c:919 [inline]
flush_commit_list+0x462/0x1d70 fs/reiserfs/journal.c:995
do_journal_end+0x38ad/0x42d0 fs/reiserfs/journal.c:4372
journal_end_sync fs/reiserfs/journal.c:3535 [inline]
__commit_trans_jl fs/reiserfs/journal.c:3877 [inline]
reiserfs_commit_for_inode+0xa1d/0xb40 fs/reiserfs/journal.c:3920
reiserfs_sync_file+0x11b/0x270 fs/reiserfs/file.c:159
generic_write_sync include/linux/fs.h:2989 [inline]
generic_file_write_iter+0x157/0x1b0 mm/filemap.c:3948
call_write_iter include/linux/fs.h:2172 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x712/0xd00 fs/read_write.c:594
ksys_pwrite64 fs/read_write.c:701 [inline]
__do_sys_pwrite64 fs/read_write.c:711 [inline]
__se_sys_pwrite64 fs/read_write.c:708 [inline]
__x64_sys_pwrite64+0x194/0x220 fs/read_write.c:708
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f48b91b6ba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f48b741e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f48b93fdfa0 RCX: 00007f48b91b6ba9
RDX: 000000000000fdef RSI: 0000200000000140 RDI: 0000000000000009
RBP: 00007f48b9239e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7c R11: 0000000000000246 R12: 0000000000000000
R13: 00007f48b93fe038 R14: 00007f48b93fdfa0 R15: 00007fff0c084868
</TASK>
==================================================================


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