syzbot
WARNING in fat12_ent_put
Status:
upstream: reported on 2026/08/17 02:15
Subsystems:
exfat
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+e64c6472a3d96a75172a@syzkaller.appspotmail.com
First crash: 10d, last: 3d12h
Sample crash report:
oom_control is deprecated and will be removed. Please report your usecase to linux-mm-@kvack.org if you depend on this functionality.
loop0: detected capacity change from 0 to 8192
------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:991 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:991, CPU#0: syz.0.0/5314
Modules linked in:
CPU: 0 UID: 0 PID: 5314 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:mark_buffer_dirty+0x299/0x410 fs/buffer.c:991
Code: 4c 89 f7 e8 99 89 d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 74 52 fb ff e8 7f 21 69 ff eb 8c e8 78 21 69 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 6a 21 69 ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc9000e0c7358 EFLAGS: 00010246
RAX: ffffffff825df458 RBX: ffff8880376f2c40 RCX: 0000000000100000
RDX: ffffc9000e9fa000 RSI: 00000000000fffff RDI: 0000000000100000
RBP: dffffc0000000001 R08: ffff8880376f2c47 R09: 1ffff11006ede588
R10: dffffc0000000000 R11: ffffed1006ede589 R12: dffffc0000000000
R13: 1ffff92001c18ea6 R14: ffffc9000e0c7530 R15: ffff888052870788
FS: 00007f2aa38786c0(0000) GS:ffff88808c526000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c60ad66168 CR3: 0000000042f56000 CR4: 0000000000352ef0
Call Trace:
<TASK>
mmb_mark_buffer_dirty+0x2c/0x1f0 fs/buffer.c:624
fat12_ent_put+0x1b7/0x2f0 fs/fat/fatent.c:173
fat_alloc_clusters+0x4e7/0xe30 fs/fat/fatent.c:508
fat_add_cluster fs/fat/inode.c:108 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x421/0xae0 fs/fat/inode.c:190
__block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2027
block_write_begin fs/buffer.c:2138 [inline]
cont_write_begin+0x71b/0xac0 fs/buffer.c:2500
fat_write_begin+0x7a/0x150 fs/fat/inode.c:230
generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4364
generic_file_write_iter+0xae/0x330 mm/filemap.c:4507
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
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: 0033:0x7f2aa299e0d9
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:00007f2aa3877fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2aa2c25fa0 RCX: 00007f2aa299e0d9
RDX: 00000000fffffdab RSI: 0000200000000000 RDI: 000000000000000d
RBP: 00007f2aa2a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2aa2c26038 R14: 00007f2aa2c25fa0 R15: 00007ffe00472218
</TASK>
* Struck through repros no longer work on HEAD.