syzbot


general protection fault in mod_objcg_mlstate

Status: moderation: reported on 2025/08/12 03:25
Subsystems: cgroups mm
[Documentation on labels]
Reported-by: syzbot+77fd5b33825fa2cab74f@syzkaller.appspotmail.com
First crash: 12d, last: 12d

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000187: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000c38-0x0000000000000c3f]
CPU: 1 UID: 0 PID: 29406 Comm: kworker/u8:19 Not tainted 6.16.0-syzkaller-06574-gd9104cec3e8f #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: kvfree_rcu_reclaim kfree_rcu_work
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:709 [inline]
RIP: 0010:account_slab_nmi_safe mm/memcontrol.c:2545 [inline]
RIP: 0010:mod_objcg_mlstate+0x138/0x260 mm/memcontrol.c:2558
Code: 00 4c 89 e0 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 0b 01 00 00 49 63 04 24 4c 8d 24 c5 00 00 00 00 4d 01 ec 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 ca 51 f7 ff 4d 8b 24 24 49 83 c4 48
RSP: 0018:ffffc9000cfb7758 EFLAGS: 00010206
RAX: 0000000000000187 RBX: ffffffff822b80b4 RCX: 42d26e8ae77b4200
RDX: 0000000000000000 RSI: ffffffff8db65e8b RDI: ffffffff8be30a00
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff822b80b4
R10: dffffc0000000000 R11: ffffed100f83c8f4 R12: 0000000000000c3b
R13: 0000000000000c3b R14: ffff8880b873b4c0 R15: ffff88813fffb400
FS:  0000000000000000(0000) GS:ffff888125d80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f390ed0c967 CR3: 000000004461e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 drain_obj_stock+0x23e/0x3c0 mm/memcontrol.c:2994
 refill_obj_stock+0x247/0x850 mm/memcontrol.c:3042
 __memcg_slab_free_hook+0x127/0x3d0 mm/memcontrol.c:3217
 memcg_slab_free_hook mm/slub.c:2206 [inline]
 slab_free_bulk mm/slub.c:4661 [inline]
 kmem_cache_free_bulk+0x46e/0x520 mm/slub.c:5246
 kfree_bulk include/linux/slab.h:794 [inline]
 kvfree_rcu_bulk+0xe5/0x1f0 mm/slab_common.c:1516
 kfree_rcu_work+0xed/0x170 mm/slab_common.c:1594
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:709 [inline]
RIP: 0010:account_slab_nmi_safe mm/memcontrol.c:2545 [inline]
RIP: 0010:mod_objcg_mlstate+0x138/0x260 mm/memcontrol.c:2558
Code: 00 4c 89 e0 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 0b 01 00 00 49 63 04 24 4c 8d 24 c5 00 00 00 00 4d 01 ec 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 ca 51 f7 ff 4d 8b 24 24 49 83 c4 48
RSP: 0018:ffffc9000cfb7758 EFLAGS: 00010206
RAX: 0000000000000187 RBX: ffffffff822b80b4 RCX: 42d26e8ae77b4200
RDX: 0000000000000000 RSI: ffffffff8db65e8b RDI: ffffffff8be30a00
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff822b80b4
R10: dffffc0000000000 R11: ffffed100f83c8f4 R12: 0000000000000c3b
R13: 0000000000000c3b R14: ffff8880b873b4c0 R15: ffff88813fffb400
FS:  0000000000000000(0000) GS:ffff888125d80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f390ed0c967 CR3: 000000004461e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	00 4c 89 e0          	add    %cl,-0x20(%rcx,%rcx,4)
   4:	48 c1 e8 03          	shr    $0x3,%rax
   8:	0f b6 04 28          	movzbl (%rax,%rbp,1),%eax
   c:	84 c0                	test   %al,%al
   e:	0f 85 0b 01 00 00    	jne    0x11f
  14:	49 63 04 24          	movslq (%r12),%rax
  18:	4c 8d 24 c5 00 00 00 	lea    0x0(,%rax,8),%r12
  1f:	00
  20:	4d 01 ec             	add    %r13,%r12
  23:	4c 89 e0             	mov    %r12,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 e7             	mov    %r12,%rdi
  33:	e8 ca 51 f7 ff       	call   0xfff75202
  38:	4d 8b 24 24          	mov    (%r12),%r12
  3c:	49 83 c4 48          	add    $0x48,%r12

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/08 03:21 net-next d9104cec3e8f 6a893178 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in mod_objcg_mlstate
* Struck through repros no longer work on HEAD.