UBSAN: array-index-out-of-bounds in apply_wqattrs_prepare

Status: upstream: reported C repro on 2026/10/16 20:57
Reported-by: syzbot+fb4591ac89cfc83156a1@syzkaller.appspotmail.com
First crash: 1d02h, last: 1d02h

Sample crash report:
================================================================================
UBSAN: array-index-out-of-bounds in kernel/locking/qspinlock.c:130:9
index 6482 is out of range for type 'unsigned long[8]'
CPU: 1 PID: 2479 Comm: syz-executor Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 dump_stack+0x15/0x1c lib/dump_stack.c:135
 ubsan_epilogue+0xe/0x40 lib/ubsan.c:148
 __ubsan_handle_out_of_bounds+0xdf/0xf0 lib/ubsan.c:347
 decode_tail kernel/locking/qspinlock.c:130 [inline]
 __pv_queued_spin_lock_slowpath+0xb03/0xb80 kernel/locking/qspinlock.c:468
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock include/linux/spinlock.h:184 [inline]
 __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_lock+0xe4/0xf0 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:355 [inline]
 get_partial_node mm/slub.c:2020 [inline]
 get_partial mm/slub.c:2125 [inline]
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x110/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
 kmem_cache_alloc_node include/linux/slab.h:426 [inline]
 alloc_unbound_pwq kernel/workqueue.c:3850 [inline]
 apply_wqattrs_prepare+0x845/0xf10 kernel/workqueue.c:3995
 apply_workqueue_attrs_locked kernel/workqueue.c:4078 [inline]
 apply_workqueue_attrs+0xd4/0x180 kernel/workqueue.c:4115
 alloc_and_link_pwqs kernel/workqueue.c:4233 [inline]
 alloc_workqueue+0xd39/0x1210 kernel/workqueue.c:4347
 tipc_crypto_start+0xd4/0x690 net/tipc/crypto.c:1494
 tipc_init_net+0x223/0x3b0 net/tipc/core.c:72
 ops_init+0x2c0/0x470 net/core/net_namespace.c:144
 setup_net+0x34f/0xae0 net/core/net_namespace.c:345
 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486
 create_new_namespaces+0x3a8/0x650 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231
 ksys_unshare+0x4fa/0x820 kernel/fork.c:3156
 __do_sys_unshare kernel/fork.c:3224 [inline]
 __se_sys_unshare kernel/fork.c:3222 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7330b7b827
Code: 73 01 c3 48 c7 c1 e8 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 10 01 00 00 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:00007ffda4c4e208 EFLAGS: 00000206
 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7330b7b827
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00007ffda4c4e260 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffda4c4e268
R13: 0000000000000002 R14: 00007ffda4c4e448 R15: 0000000000000000
================================================================================
general protection fault, probably for non-canonical address 0xff6cc73b9f6d798a: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xfb6659dcfb6bcc50-0xfb6659dcfb6bcc57]
CPU: 1 PID: 2479 Comm: syz-executor Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:__pv_queued_spin_lock_slowpath+0x2cc/0xb80 kernel/locking/qspinlock.c:471
Code: 74 14 48 89 54 24 18 48 8b 7c 24 18 e8 6d 5e 53 00 48 8b 54 24 18 4c 03 2a 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 e6 5e 53 00 48 8b 44 24 40 49 89 45
RSP: 0018:ffffc90001637580 EFLAGS: 00010803

RAX: 1f6ccb3b9f6d798a RBX: ffff88810006c000 RCX: dffffc0000000000
RDX: ffffffff85c01150 RSI: 0000000000000027 RDI: 00000000ffffffff
RBP: ffffc90001637670 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf848 R12: 1ffff1103ee2ae51
R13: fb6659dcfb6bcc56 R14: 1ffff1102000d800 R15: ffff8881f7157294
FS:  0000555560c3e500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6a004c9300 CR3: 000000011238e000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock include/linux/spinlock.h:184 [inline]
 __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_lock+0xe4/0xf0 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:355 [inline]
 get_partial_node mm/slub.c:2020 [inline]
 get_partial mm/slub.c:2125 [inline]
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x110/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
 kmem_cache_alloc_node include/linux/slab.h:426 [inline]
 alloc_unbound_pwq kernel/workqueue.c:3850 [inline]
 apply_wqattrs_prepare+0x845/0xf10 kernel/workqueue.c:3995
 apply_workqueue_attrs_locked kernel/workqueue.c:4078 [inline]
 apply_workqueue_attrs+0xd4/0x180 kernel/workqueue.c:4115
 alloc_and_link_pwqs kernel/workqueue.c:4233 [inline]
 alloc_workqueue+0xd39/0x1210 kernel/workqueue.c:4347
 tipc_crypto_start+0xd4/0x690 net/tipc/crypto.c:1494
 tipc_init_net+0x223/0x3b0 net/tipc/core.c:72
 ops_init+0x2c0/0x470 net/core/net_namespace.c:144
 setup_net+0x34f/0xae0 net/core/net_namespace.c:345
 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486
 create_new_namespaces+0x3a8/0x650 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231
 ksys_unshare+0x4fa/0x820 kernel/fork.c:3156
 __do_sys_unshare kernel/fork.c:3224 [inline]
 __se_sys_unshare kernel/fork.c:3222 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7330b7b827
Code: 73 01 c3 48 c7 c1 e8 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 10 01 00 00 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:00007ffda4c4e208 EFLAGS: 00000206
 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7330b7b827
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00007ffda4c4e260 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffda4c4e268
R13: 0000000000000002 R14: 00007ffda4c4e448 R15: 0000000000000000
Modules linked in:

---[ end trace 67f8347f61551633 ]---
RIP: 0010:__pv_queued_spin_lock_slowpath+0x2cc/0xb80 kernel/locking/qspinlock.c:471
Code: 74 14 48 89 54 24 18 48 8b 7c 24 18 e8 6d 5e 53 00 48 8b 54 24 18 4c 03 2a 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 e6 5e 53 00 48 8b 44 24 40 49 89 45
RSP: 0018:ffffc90001637580 EFLAGS: 00010803

RAX: 1f6ccb3b9f6d798a RBX: ffff88810006c000 RCX: dffffc0000000000
RDX: ffffffff85c01150 RSI: 0000000000000027 RDI: 00000000ffffffff
RBP: ffffc90001637670 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf848 R12: 1ffff1103ee2ae51
R13: fb6659dcfb6bcc56 R14: 1ffff1102000d800 R15: ffff8881f7157294
FS:  0000555560c3e500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6a004c9300 CR3: 000000011238e000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000
----------------
Code disassembly (best guess):
   0:	74 14                	je     0x16
   2:	48 89 54 24 18       	mov    %rdx,0x18(%rsp)
   7:	48 8b 7c 24 18       	mov    0x18(%rsp),%rdi
   c:	e8 6d 5e 53 00       	call   0x535e7e
  11:	48 8b 54 24 18       	mov    0x18(%rsp),%rdx
  16:	4c 03 2a             	add    (%rdx),%r13
  19:	4c 89 e8             	mov    %r13,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 ef             	mov    %r13,%rdi
  33:	e8 e6 5e 53 00       	call   0x535f1e
  38:	48 8b 44 24 40       	mov    0x40(%rsp),%rax
  3d:	49                   	rex.WB
  3e:	89                   	.byte 0x89
  3f:	45                   	rex.RB

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/16 20:55 android13-5.10-lts f5932bf046b5 4c840a2f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 UBSAN: array-index-out-of-bounds in apply_wqattrs_prepare
* Struck through repros no longer work on HEAD.