syzbot


BUG: unable to handle kernel NULL pointer dereference in deactivate_slab (3)

Status: moderation: reported on 2025/10/01 15:55
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+805668f2653c57255273@syzkaller.appspotmail.com
First crash: 6d10h, last: 6d10h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: unable to handle kernel NULL pointer dereference in deactivate_slab kernel 10 14 465d 494d 0/29 auto-obsoleted due to no activity on 2024/09/04 01:58
upstream BUG: unable to handle kernel NULL pointer dereference in deactivate_slab (2) mm 10 9 143d 294d 0/29 auto-obsoleted due to no activity on 2025/08/21 07:50
upstream KMSAN: kernel-infoleak in v4l2_compat_put_array_args media 17 8 1050d 1354d 22/29 fixed on 2023/02/24 13:50

Sample crash report:
BUG: kernel NULL pointer dereference, address: 0000000000000001
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 977 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: slub_flushwq flush_cpu_slab
RIP: 0010:PagePoisoned include/linux/page-flags.h:335 [inline]
RIP: 0010:page_to_nid include/linux/mm.h:1516 [inline]
RIP: 0010:folio_nid include/linux/mm.h:1522 [inline]
RIP: 0010:slab_nid mm/slab.h:177 [inline]
RIP: 0010:deactivate_slab+0x1e/0x3f0 mm/slub.c:3109
Code: 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 41 55 41 54 53 48 83 ec 48 49 89 f7 65 48 8b 05 97 c9 e2 0f 48 89 44 24 40 <48> 8b 06 48 83 f8 ff 0f 84 9e 03 00 00 49 89 d5 49 89 fc 48 c1 e8
RSP: 0018:ffffc900048af9d0 EFLAGS: 00010282
RAX: bb2db7d1442f0800 RBX: ffff88803c71b8c0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88803c71b8c0
RBP: ffffc900048afc70 R08: ffffffff8f1d6237 R09: 1ffffffff1e3ac46
R10: dffffc0000000000 R11: fffffbfff1e3ac47 R12: ffffe8ffffc7ddf0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881268bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000001 CR3: 0000000036bfc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 flush_slab mm/slub.c:3329 [inline]
 flush_cpu_slab+0xc6/0x1c0 mm/slub.c:3375
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
CR2: 0000000000000001
---[ end trace 0000000000000000 ]---
RIP: 0010:PagePoisoned include/linux/page-flags.h:335 [inline]
RIP: 0010:page_to_nid include/linux/mm.h:1516 [inline]
RIP: 0010:folio_nid include/linux/mm.h:1522 [inline]
RIP: 0010:slab_nid mm/slab.h:177 [inline]
RIP: 0010:deactivate_slab+0x1e/0x3f0 mm/slub.c:3109
Code: 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 41 55 41 54 53 48 83 ec 48 49 89 f7 65 48 8b 05 97 c9 e2 0f 48 89 44 24 40 <48> 8b 06 48 83 f8 ff 0f 84 9e 03 00 00 49 89 d5 49 89 fc 48 c1 e8
RSP: 0018:ffffc900048af9d0 EFLAGS: 00010282
RAX: bb2db7d1442f0800 RBX: ffff88803c71b8c0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88803c71b8c0
RBP: ffffc900048afc70 R08: ffffffff8f1d6237 R09: 1ffffffff1e3ac46
R10: dffffc0000000000 R11: fffffbfff1e3ac47 R12: ffffe8ffffc7ddf0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881268bc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000001 CR3: 0000000036bfc000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	90                   	nop
   3:	90                   	nop
   4:	90                   	nop
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	55                   	push   %rbp
   d:	41 57                	push   %r15
   f:	41 56                	push   %r14
  11:	41 55                	push   %r13
  13:	41 54                	push   %r12
  15:	53                   	push   %rbx
  16:	48 83 ec 48          	sub    $0x48,%rsp
  1a:	49 89 f7             	mov    %rsi,%r15
  1d:	65 48 8b 05 97 c9 e2 	mov    %gs:0xfe2c997(%rip),%rax        # 0xfe2c9bc
  24:	0f
  25:	48 89 44 24 40       	mov    %rax,0x40(%rsp)
* 2a:	48 8b 06             	mov    (%rsi),%rax <-- trapping instruction
  2d:	48 83 f8 ff          	cmp    $0xffffffffffffffff,%rax
  31:	0f 84 9e 03 00 00    	je     0x3d5
  37:	49 89 d5             	mov    %rdx,%r13
  3a:	49 89 fc             	mov    %rdi,%r12
  3d:	48                   	rex.W
  3e:	c1                   	.byte 0xc1
  3f:	e8                   	.byte 0xe8

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/27 15:43 upstream fec734e8d564 001c9061 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs BUG: unable to handle kernel NULL pointer dereference in deactivate_slab
* Struck through repros no longer work on HEAD.