syzbot
WARNING in vfat_update_dotdot_de
Status:
upstream: reported C repro on 2026/09/14 16:38
Subsystems:
exfat
Labels:
prio:low
[Documentation on labels]
Reported-by: syzbot+b0aebd03565f5774f7f8@syzkaller.appspotmail.com
First crash: 2d23h, last: 1d22h
Sample crash report:
loop0: rw=8912896, sector=102, nr_sectors = 1 limit=63
syz.0.17: attempt to access beyond end of device
loop0: rw=8912896, sector=103, nr_sectors = 1 limit=63
syz.0.17: attempt to access beyond end of device
loop0: rw=8390657, sector=98, nr_sectors = 1 limit=63
Buffer I/O error on dev loop0, logical block 98, lost sync page write
------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:991 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:991, CPU#0: syz.0.17/6146
Modules linked in:
CPU: 0 UID: 0 PID: 6146 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
RIP: 0010:mark_buffer_dirty+0x299/0x410 fs/buffer.c:991
Code: 4c 89 f7 e8 a9 01 d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 74 52 fb ff e8 ef 00 68 ff eb 8c e8 e8 00 68 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 da 00 68 ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc90003b57858 EFLAGS: 00010293
RAX: ffffffff825fc9c8 RBX: ffff888076b98460 RCX: ffff888020348000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: dffffc0000000001 R08: ffff888076b98467 R09: 1ffff1100ed7308c
R10: dffffc0000000000 R11: ffffed100ed7308d R12: ffff88806768a434
R13: 0000000000000000 R14: ffff8880544440b0 R15: ffff88807688ba08
FS: 00007fa0804ca6c0(0000) GS:ffff888124cd2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdc870d998 CR3: 0000000035986000 CR4: 0000000000350ef0
Call Trace:
<TASK>
mmb_mark_buffer_dirty+0x2c/0x1f0 fs/buffer.c:624
vfat_update_dotdot_de+0x90/0x1c0 fs/fat/namei_vfat.c:917
vfat_rename_exchange fs/fat/namei_vfat.c:1140 [inline]
vfat_rename2+0xe3e/0x1c90 fs/fat/namei_vfat.c:1171
vfs_rename+0xbd9/0xef0 fs/namei.c:6208
filename_renameat2+0x533/0x9a0 fs/namei.c:6326
__do_sys_renameat2 fs/namei.c:6355 [inline]
__se_sys_renameat2+0x5a/0x2c0 fs/namei.c:6350
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa07f59e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa0804ca028 EFLAGS: 00000246 ORIG_RAX: 000000000000013c
RAX: ffffffffffffffda RBX: 00007fa07f826090 RCX: 00007fa07f59e159
RDX: ffffffffffffff9c RSI: 0000200000000480 RDI: ffffffffffffff9c
RBP: 00007fa07f63503b R08: 0000000000000002 R09: 0000000000000000
R10: 00002000000004c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa07f826128 R14: 00007fa07f826090 R15: 00007ffc6d0e6af8
</TASK>
* Struck through repros no longer work on HEAD.