[v6.6] BUG: unable to handle kernel paging request in udf_unlink

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12fd4d58580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=3aec4eac211b2b7142b7
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17aa131a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1765f51a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e9a108d9744c/mount_1.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3aec4e...@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: ffffed10199dfec4
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffee067 P4D 23ffee067 PUD 13fff5067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5884 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
RIP: 0010:udf_add_fid_counter fs/udf/namei.c:-1 [inline]
RIP: 0010:udf_unlink+0x39e/0x6d0 fs/udf/namei.c:565
Code: 43 80 3c 3e 00 74 08 4c 89 e7 e8 ed 80 e6 fe bf c0 00 00 00 49 03 3c 24 31 f6 e8 ed 93 79 07 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 20 02 00 00 ff 0b 43 80 3c 3e 00 74 08
RSP: 0018:ffffc90003367be0 EFLAGS: 00010a02
RAX: 1ffff110199dfec4 RBX: ffff8880cceff620 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: 00000000ffffffff
RBP: ffffc90003367d80 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: ffff88802e0ac630
R13: ffff888063848e28 R14: 1ffff11005c158c6 R15: dffffc0000000000
FS: 000055557962b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed10199dfec4 CR3: 000000002ec08000 CR4: 00000000003506e0
Call Trace:
<TASK>
vfs_unlink+0x389/0x600 fs/namei.c:4333
do_unlinkat+0x328/0x570 fs/namei.c:4399
__do_sys_unlink fs/namei.c:4447 [inline]
__se_sys_unlink fs/namei.c:4445 [inline]
__x64_sys_unlink+0x49/0x50 fs/namei.c:4445
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f11a338ecf7
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 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:00007ffc37a4abd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f11a338ecf7
RDX: 00007ffc37a4ac00 RSI: 00007ffc37a4ac90 RDI: 00007ffc37a4ac90
RBP: 00007ffc37a4ac90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc37a4bd80
R13: 00007f11a3413d7d R14: 00000000000170fd R15: 00007ffc37a4df40
</TASK>
Modules linked in:
CR2: ffffed10199dfec4
---[ end trace 0000000000000000 ]---
RIP: 0010:le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
RIP: 0010:udf_add_fid_counter fs/udf/namei.c:-1 [inline]
RIP: 0010:udf_unlink+0x39e/0x6d0 fs/udf/namei.c:565
Code: 43 80 3c 3e 00 74 08 4c 89 e7 e8 ed 80 e6 fe bf c0 00 00 00 49 03 3c 24 31 f6 e8 ed 93 79 07 48 83 c3 20 48 89 d8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 20 02 00 00 ff 0b 43 80 3c 3e 00 74 08
RSP: 0018:ffffc90003367be0 EFLAGS: 00010a02
RAX: 1ffff110199dfec4 RBX: ffff8880cceff620 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8afc6f60 RDI: 00000000ffffffff
RBP: ffffc90003367d80 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: ffff88802e0ac630
R13: ffff888063848e28 R14: 1ffff11005c158c6 R15: dffffc0000000000
FS: 000055557962b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed10199dfec4 CR3: 000000002ec08000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
0: 43 80 3c 3e 00 cmpb $0x0,(%r14,%r15,1)
5: 74 08 je 0xf
7: 4c 89 e7 mov %r12,%rdi
a: e8 ed 80 e6 fe call 0xfee680fc
f: bf c0 00 00 00 mov $0xc0,%edi
14: 49 03 3c 24 add (%r12),%rdi
18: 31 f6 xor %esi,%esi
1a: e8 ed 93 79 07 call 0x779940c
1f: 48 83 c3 20 add $0x20,%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 20 02 00 00 jne 0x257
37: ff 0b decl (%rbx)
39: 43 80 3c 3e 00 cmpb $0x0,(%r14,%r15,1)
3e: 74 08 je 0x48


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