[moderation] [fs?] general protection fault in ufs_sync_fs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110313b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e38b15c29e6a1d9
dashboard link: https://syzkaller.appspot.com/bug?extid=7e1eaaa4585fc7dacdd9
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9bf3ffd710de/disk-848acc8f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/770c0a63a80c/vmlinux-848acc8f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c54f9393cb03/bzImage-848acc8f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7e1eaa...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000003c: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000001e0-0x00000000000001e7]
CPU: 0 UID: 0 PID: 12816 Comm: syz.0.2075 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:625 [inline]
RIP: 0010:__mutex_lock+0x149/0x1550 kernel/locking/mutex.c:821
Code: c0 80 a5 78 9a 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 35 12 00 00 83 3d 75 f5 a5 0e 00 75 22 49 8d 7c 24 58 48 89 f8 48 c1 e8 03 <80> 3c 18 00 74 05 e8 6c fb 61 f6 4d 39 64 24 58 0f 85 48 11 00 00
RSP: 0018:ffffc90005a37900 EFLAGS: 00010216
RAX: 000000000000003c RBX: dffffc0000000000 RCX: ffffffff9a78a503
RDX: 0000000000000000 RSI: ffffffff8e4b420d RDI: 00000000000001e0
RBP: ffffc90005a37a98 R08: ffffc90005a37a07 R09: ffffc90005a379e0
R10: dffffc0000000000 R11: fffff52000b46f41 R12: 0000000000000188
R13: 0000000000000000 R14: 1ffff92000b46f34 R15: 0000000000000000
FS: 00007f90f4be26c0(0000) GS:ffff888124f4b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5926c4e00d CR3: 000000002a90c000 CR4: 0000000000350ef0
Call Trace:
<TASK>
ufs_sync_fs+0x59/0x780 fs/ufs/super.c:631
sync_filesystem+0xee/0x230 fs/sync.c:56
generic_shutdown_super+0x77/0x2d0 fs/super.c:626
kill_block_super+0x44/0x90 fs/super.c:1671
deactivate_locked_super+0xbc/0x130 fs/super.c:477
get_tree_bdev_flags+0x44e/0x4f0 fs/super.c:1642
vfs_get_tree+0x92/0x2a0 fs/super.c:1700
fc_mount fs/namespace.c:1198 [inline]
do_new_mount_fc fs/namespace.c:3765 [inline]
do_new_mount+0x319/0xdc0 fs/namespace.c:3841
do_mount fs/namespace.c:4174 [inline]
__do_sys_mount fs/namespace.c:4390 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4367
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f90f3d9e019
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:00007f90f4be2028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f90f4025fa0 RCX: 00007f90f3d9e019
RDX: 0000200000004000 RSI: 0000200000003000 RDI: 0000200000000040
RBP: 00007f90f3e3500c R08: 0000200000005000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f90f4026038 R14: 00007f90f4025fa0 R15: 00007ffca4f22028
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:625 [inline]
RIP: 0010:__mutex_lock+0x149/0x1550 kernel/locking/mutex.c:821
Code: c0 80 a5 78 9a 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 35 12 00 00 83 3d 75 f5 a5 0e 00 75 22 49 8d 7c 24 58 48 89 f8 48 c1 e8 03 <80> 3c 18 00 74 05 e8 6c fb 61 f6 4d 39 64 24 58 0f 85 48 11 00 00
RSP: 0018:ffffc90005a37900 EFLAGS: 00010216
RAX: 000000000000003c RBX: dffffc0000000000 RCX: ffffffff9a78a503
RDX: 0000000000000000 RSI: ffffffff8e4b420d RDI: 00000000000001e0
RBP: ffffc90005a37a98 R08: ffffc90005a37a07 R09: ffffc90005a379e0
R10: dffffc0000000000 R11: fffff52000b46f41 R12: 0000000000000188
R13: 0000000000000000 R14: 1ffff92000b46f34 R15: 0000000000000000
FS: 00007f90f4be26c0(0000) GS:ffff88812504b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b341f8ff8 CR3: 000000002a90c000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: c0 80 a5 78 9a 48 c1 rolb $0xc1,0x489a78a5(%rax)
7: e8 03 0f b6 04 call 0x4b60f0f
c: 18 84 c0 0f 85 35 12 sbb %al,0x1235850f(%rax,%rax,8)
13: 00 00 add %al,(%rax)
15: 83 3d 75 f5 a5 0e 00 cmpl $0x0,0xea5f575(%rip) # 0xea5f591
1c: 75 22 jne 0x40
1e: 49 8d 7c 24 58 lea 0x58(%r12),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 74 05 je 0x35
30: e8 6c fb 61 f6 call 0xf661fba1
35: 4d 39 64 24 58 cmp %r12,0x58(%r12)
3a: 0f 85 48 11 00 00 jne 0x1188


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