[syzbot] [exfat?] WARNING in vfat_update_dotdot_de

[syzbot] [exfat?] WARNING in vfat_update_dotdot_de

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    5225b8eec4c9 mailmap: update entry for Jens Axboe
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11cd61f9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=b0aebd03565f5774f7f8
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11b455f9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13a1b615580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fdabe739a017/disk-5225b8ee.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ef60d7040756/vmlinux-5225b8ee.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ccb7b942e430/bzImage-5225b8ee.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/be5074fab5f0/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=16cd61f9580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0aebd03565f5774f7f8@syzkaller.appspotmail.com

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>


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