syzbot


BUG: unable to handle kernel paging request in __lookup_slow

Status: upstream: reported C repro on 2026/05/03 18:11
Reported-by: syzbot+3dc631faa211d0dce7f0@syzkaller.appspotmail.com
First crash: 2d18h, last: 2d18h
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow origin:downstream 10 C 1 17d 18d 0/2 upstream: reported C repro on 2026/04/18 02:32
upstream BUG: unable to handle kernel NULL pointer dereference in __lookup_slow fs 10 C inconclusive done 3 1905d 2046d 19/29 fixed on 2021/03/10 01:48
linux-4.19 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow (2) 10 C done 15 1728d 1851d 1/1 fixed on 2021/09/13 16:54
linux-5.15 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow origin:lts-only 10 C done 5 520d 528d 0/3 auto-obsoleted due to no activity on 2025/03/12 04:53
upstream BUG: unable to handle kernel NULL pointer dereference in __lookup_slow (2) fs 10 C inconclusive 4 1766d 1849d 0/29 auto-obsoleted due to no activity on 2023/04/14 10:28
linux-4.19 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow 10 C done 23 1884d 2042d 1/1 fixed on 2021/04/10 11:48
upstream BUG: unable to handle kernel NULL pointer dereference in __lookup_slow (3) overlayfs 10 C inconclusive done 135 529d 738d 0/29 auto-obsoleted due to no activity on 2025/01/31 21:09
android-5-10 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow 10 C 1 13d 122d 0/2 upstream: reported C repro on 2026/01/03 23:57

Sample crash report:
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
exFAT-fs (loop2): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
exFAT-fs (loop2): Medium has reported failures. Some data may be lost.
exFAT-fs (loop2): failed to load upcase table (idx : 0x00010000, chksum : 0xe2e35dda, utbl_chksum : 0xe619d30d)
BUG: unable to handle page fault for address: fffffffffffffffc
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7012067 P4D 7012067 PUD 7014067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 373 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__lookup_slow+0x2ca/0x410 fs/namei.c:1697
Code: 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 2b 6f f4 ff 48 8b 7c 24 08 4c 89 ee 8b 54 24 04 4c 8b 1b 41 ba 4f 27 89 b6 <45> 03 53 fc 74 02 0f 0b 41 ff d3 48 89 c3 43 0f b6 04 26 84 c0 0f
RSP: 0018:ffffc900009d79e0 EFLAGS: 00010246
RAX: 1ffffffff0b6c768 RBX: ffffffff85b63b40 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888111144220 RDI: ffff888123f10d30
RBP: ffffc900009d7ab0 R08: ffffffff87bd1517 R09: 1ffffffff0f7a2a2
R10: 00000000b689274f R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888111144220 R14: 1ffff11022228844 R15: 1ffff9200013af40
FS:  000055555cee3500(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000012be41000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lookup_one_len+0x19d/0x2e0 fs/namei.c:2747
 incfs_lookup_dentry+0x60/0xb0 fs/incfs/data_mgmt.c:210
 ioctl_create_file fs/incfs/pseudo_files.c:556 [inline]
 pending_reads_dispatch_ioctl+0x1618/0x1e60 fs/incfs/pseudo_files.c:1030
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x12f/0x1b0 fs/ioctl.c:856
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:856
 x64_sys_call+0x58b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc7fb59cdd9
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:00007ffeef51d6e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc7fb815fa0 RCX: 00007fc7fb59cdd9
RDX: 00002000000000c0 RSI: 00000000c058671e RDI: 0000000000000005
RBP: 00007fc7fb632d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc7fb815fac R14: 00007fc7fb815fa0 R15: 00007fc7fb815fa0
 </TASK>
Modules linked in:
CR2: fffffffffffffffc
---[ end trace 0000000000000000 ]---
RIP: 0010:__lookup_slow+0x2ca/0x410 fs/namei.c:1697
Code: 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 2b 6f f4 ff 48 8b 7c 24 08 4c 89 ee 8b 54 24 04 4c 8b 1b 41 ba 4f 27 89 b6 <45> 03 53 fc 74 02 0f 0b 41 ff d3 48 89 c3 43 0f b6 04 26 84 c0 0f
RSP: 0018:ffffc900009d79e0 EFLAGS: 00010246
RAX: 1ffffffff0b6c768 RBX: ffffffff85b63b40 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888111144220 RDI: ffff888123f10d30
RBP: ffffc900009d7ab0 R08: ffffffff87bd1517 R09: 1ffffffff0f7a2a2
R10: 00000000b689274f R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888111144220 R14: 1ffff11022228844 R15: 1ffff9200013af40
FS:  000055555cee3500(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000012be41000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 d8                	mov    %ebx,%eax
   2:	48 c1 e8 03          	shr    $0x3,%rax
   6:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
   b:	74 08                	je     0x15
   d:	48 89 df             	mov    %rbx,%rdi
  10:	e8 2b 6f f4 ff       	call   0xfff46f40
  15:	48 8b 7c 24 08       	mov    0x8(%rsp),%rdi
  1a:	4c 89 ee             	mov    %r13,%rsi
  1d:	8b 54 24 04          	mov    0x4(%rsp),%edx
  21:	4c 8b 1b             	mov    (%rbx),%r11
  24:	41 ba 4f 27 89 b6    	mov    $0xb689274f,%r10d
* 2a:	45 03 53 fc          	add    -0x4(%r11),%r10d <-- trapping instruction
  2e:	74 02                	je     0x32
  30:	0f 0b                	ud2
  32:	41 ff d3             	call   *%r11
  35:	48 89 c3             	mov    %rax,%rbx
  38:	43 0f b6 04 26       	movzbl (%r14,%r12,1),%eax
  3d:	84 c0                	test   %al,%al
  3f:	0f                   	.byte 0xf

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/03 18:10 android14-6.1 1e4e23ff0f90 a0d91488 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (clean fs)] ci2-android-6-1 BUG: unable to handle kernel paging request in __lookup_slow
* Struck through repros no longer work on HEAD.