syzbot


BUG: unable to handle kernel paging request in udf_unlink

Status: upstream: reported C repro on 2025/12/19 05:05
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+3aec4eac211b2b7142b7@syzkaller.appspotmail.com
First crash: 28d, last: 3d00h
Bug presence (1)
Date Name Commit Repro Result
2025/12/22 upstream (ToT) 9448598b22c5 C [report] WARNING in udf_unlink

Sample crash report:
BUG: unable to handle page fault for address: ffffed101ac7f763
#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: 0 PID: 5877 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 3d 72 e6 fe bf c0 00 00 00 49 03 3c 24 31 f6 e8 dd f8 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:ffffc900048efbe0 EFLAGS: 00010a06
RAX: 1ffff1101ac7f763 RBX: ffff8880d63fbb18 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8afc7380 RDI: 00000000ffffffff
RBP: ffffc900048efd80 R08: ffffffff8e4a39ef R09: 1ffffffff1c9473d
R10: dffffc0000000000 R11: fffffbfff1c9473e R12: ffff88807a238630
R13: ffff88806dde8158 R14: 1ffff1100f4470c6 R15: dffffc0000000000
FS:  0000555559e14500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed101ac7f763 CR3: 000000002b498000 CR4: 00000000003506f0
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:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdd1178ecf7
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:00007ffc4f466488 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdd1178ecf7
RDX: 00007ffc4f4664b0 RSI: 00007ffc4f466540 RDI: 00007ffc4f466540
RBP: 00007ffc4f466540 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffc4f467630
R13: 00007fdd11813d7d R14: 0000000000019915 R15: 00007ffc4f4697f0
 </TASK>
Modules linked in:
CR2: ffffed101ac7f763
---[ 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 3d 72 e6 fe bf c0 00 00 00 49 03 3c 24 31 f6 e8 dd f8 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:ffffc900048efbe0 EFLAGS: 00010a06
RAX: 1ffff1101ac7f763 RBX: ffff8880d63fbb18 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8afc7380 RDI: 00000000ffffffff
RBP: ffffc900048efd80 R08: ffffffff8e4a39ef R09: 1ffffffff1c9473d
R10: dffffc0000000000 R11: fffffbfff1c9473e R12: ffff88807a238630
R13: ffff88806dde8158 R14: 1ffff1100f4470c6 R15: dffffc0000000000
FS:  0000555559e14500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed101ac7f763 CR3: 000000002b498000 CR4: 00000000003506f0
----------------
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 3d 72 e6 fe       	call   0xfee6724c
   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 dd f8 79 07       	call   0x779f8fc
  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

Crashes (12):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/14 03:34 linux-6.6.y c596736dadab d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2026/01/14 01:58 linux-6.6.y c596736dadab d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/24 23:30 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/19 13:18 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/19 10:31 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/19 08:01 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/19 06:48 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/19 05:04 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-6-kasan BUG: unable to handle kernel paging request in udf_unlink
2025/12/22 10:06 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-linux-6-6-kasan KASAN: use-after-free Read in udf_unlink
2025/12/22 08:16 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-linux-6-6-kasan KASAN: use-after-free Read in udf_unlink
2025/12/19 11:53 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Read in udf_unlink
2025/12/19 09:17 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2 (clean fs)] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in udf_unlink
* Struck through repros no longer work on HEAD.