syzbot


BUG: unable to handle kernel NULL pointer dereference in __lookup_slow

Status: upstream: reported C repro on 2026/04/18 02:32
Bug presence: origin:downstream
[Documentation on labels]
Reported-by: syzbot+b335889a8d156d1cad3f@syzkaller.appspotmail.com
First crash: 1d16h, last: 20h36m
Bug presence (3)
Date Name Commit Repro Result
2026/04/18 android13-5.15-lts (ToT) 7fad219d720d C [report] BUG: unable to handle kernel NULL pointer dereference in __lookup_slow
2026/04/18 lts (merge base) 91d48252ad4b C Didn't crash
2026/04/18 upstream (ToT) eb5249b12507 C Didn't crash
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: unable to handle kernel NULL pointer dereference in __lookup_slow fs 10 C inconclusive done 3 1889d 2029d 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 1711d 1834d 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 503d 511d 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 1749d 1832d 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 1867d 2025d 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 512d 721d 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 27d 105d 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: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 12db61067 P4D 12db61067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 357 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000b779d8 EFLAGS: 00010246
RAX: 1ffffffff0aa0cd8 RBX: 1ffff1102137cf10 RCX: ffff8881103be2c0
RDX: 0000000000000000 RSI: ffff888109be7880 RDI: ffff888121372350
RBP: ffffc90000b77ab0 R08: ffffffff8711f5b7 R09: 1ffffffff0e23eb6
R10: dffffc0000000000 R11: fffffbfff0e23eb7 R12: dffffc0000000000
R13: ffff888109be7880 R14: ffffffff855066c0 R15: 1ffff9200016ef40
FS:  0000555563cec500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000012db51000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __lookup_slow+0x2b8/0x410 fs/namei.c:1671
 lookup_one_len+0x19d/0x2d0 fs/namei.c:2726
 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+0x161e/0x1e70 fs/incfs/pseudo_files.c:1030
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:860
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:860
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff9942a0819
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:00007fff2a4e9918 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff994519fa0 RCX: 00007ff9942a0819
RDX: 00002000000000c0 RSI: 00000000c058671e RDI: 0000000000000005
RBP: 00007ff994336c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff994519fac R14: 00007ff994519fa0 R15: 00007ff994519fa0
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace f62f978b3530e73e ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000b779d8 EFLAGS: 00010246
RAX: 1ffffffff0aa0cd8 RBX: 1ffff1102137cf10 RCX: ffff8881103be2c0
RDX: 0000000000000000 RSI: ffff888109be7880 RDI: ffff888121372350
RBP: ffffc90000b77ab0 R08: ffffffff8711f5b7 R09: 1ffffffff0e23eb6
R10: dffffc0000000000 R11: fffffbfff0e23eb7 R12: dffffc0000000000
R13: ffff888109be7880 R14: ffffffff855066c0 R15: 1ffff9200016ef40
FS:  0000555563cec500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000012db51000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/18 02:30 android13-5.15-lts 7fad219d720d 24ecfc1e .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-5-15 BUG: unable to handle kernel NULL pointer dereference in __lookup_slow
* Struck through repros no longer work on HEAD.