syzbot


WARNING: ODEBUG bug in handle_softirqs (2)

Status: upstream: reported on 2026/05/29 15:00
Reported-by: syzbot+591c4a50be036eba9374@syzkaller.appspotmail.com
First crash: 6d17h, last: 6d17h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 WARNING: ODEBUG bug in handle_softirqs -1 3 100d 129d 0/2 auto-obsoleted due to no activity on 2026/06/04 14:54
linux-6.1 WARNING: ODEBUG bug in handle_softirqs -1 4 119d 120d 0/3 auto-obsoleted due to no activity on 2026/05/16 13:07
upstream WARNING: ODEBUG bug in handle_softirqs hams prio:high -1 C error 4394 14d 281d 0/29 upstream: reported C repro on 2025/08/27 17:00

Sample crash report:
------------[ cut here ]------------
ODEBUG: free active (active state 0) object type: timer_list hint: br_ip6_multicast_port_query_expired+0x0/0x20
WARNING: CPU: 1 PID: 11895 at lib/debugobjects.c:518 debug_print_object lib/debugobjects.c:515 [inline]
WARNING: CPU: 1 PID: 11895 at lib/debugobjects.c:518 __debug_check_no_obj_freed lib/debugobjects.c:979 [inline]
WARNING: CPU: 1 PID: 11895 at lib/debugobjects.c:518 debug_check_no_obj_freed+0x43c/0x530 lib/debugobjects.c:1009
Modules linked in:
CPU: 1 PID: 11895 Comm: syz.4.2377 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:debug_print_object lib/debugobjects.c:515 [inline]
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:979 [inline]
RIP: 0010:debug_check_no_obj_freed+0x43c/0x530 lib/debugobjects.c:1009
Code: ef e8 98 af bd fd 4c 8b 45 00 48 c7 c7 c0 24 df 8a 48 c7 c6 80 21 df 8a 48 c7 c2 20 26 df 8a 8b 0c 24 4d 89 e9 e8 b4 11 38 fd <0f> 0b 4c 8b 6c 24 18 48 b9 00 00 00 00 00 fc ff df ff 05 75 5d 0a
RSP: 0018:ffffc900001e0a18 EFLAGS: 00010246
RAX: efd435b75458b800 RBX: ffffffff96ec2be8 RCX: ffff888024cc0000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffffffff8a8df720 R08: ffffc900001e06a7 R09: 1ffff9200003c0d4
R10: dffffc0000000000 R11: fffff5200003c0d5 R12: ffff8880573c5400
R13: ffffffff8915c690 R14: ffff8880573c5000 R15: ffff8880573c5278
FS:  00007f16525306c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f90193456b8 CR3: 0000000073c4e000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 slab_free_hook mm/slub.c:1704 [inline]
 slab_free_freelist_hook+0xd2/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 kobject_cleanup lib/kobject.c:681 [inline]
 kobject_release lib/kobject.c:712 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21d/0x460 lib/kobject.c:729
 rcu_do_batch kernel/rcu/tree.c:2297 [inline]
 rcu_core+0xa99/0x1740 kernel/rcu/tree.c:2557
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lockdep_unregister_key+0x4e8/0x550 kernel/locking/lockdep.c:6370
Code: d1 aa 90 48 c7 c6 70 f7 64 81 e8 73 a8 07 00 e8 de bb 07 00 e9 5c fc ff ff e8 d4 9e c9 08 41 f7 c4 00 02 00 00 74 d1 fb 84 db <75> d0 eb e1 0f 0b eb 88 0f 0b e9 f8 fe ff ff 0f 0b e9 45 ff ff ff
RSP: 0018:ffffc9000432f820 EFLAGS: 00000202
RAX: dffffc0000000000 RBX: ffff888027179a01 RCX: efd435b75458b800
RDX: 0000000000000001 RSI: ffffffff8a8c2680 RDI: ffffffff8adf1b60
RBP: ffffc9000432f900 R08: ffffffff90aafa6f R09: 1ffffffff2155f4d
R10: dffffc0000000000 R11: fffffbfff2155f4e R12: 0000000000000a06
R13: ffff888027179a99 R14: ffffffff90aad198 R15: 1ffff92000865f08
 __qdisc_destroy+0x128/0x430 net/sched/sch_generic.c:1081
 netdev_for_each_tx_queue include/linux/netdevice.h:2465 [inline]
 dev_shutdown+0x92/0x440 net/sched/sch_generic.c:1465
 unregister_netdevice_many_notify+0xa76/0x19c0 net/core/dev.c:11014
 unregister_netdevice_many net/core/dev.c:11077 [inline]
 unregister_netdevice_queue+0x328/0x370 net/core/dev.c:10960
 br_del_bridge+0xb9/0xf0 net/bridge/br_if.c:496
 br_ioctl_stub+0x6e0/0xcf0 net/bridge/br_ioctl.c:444
 br_ioctl_call net/socket.c:1175 [inline]
 sock_ioctl+0x494/0x710 net/socket.c:1274
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 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: 0033:0x7f165159ce59
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:00007f1652530028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1651815fa0 RCX: 00007f165159ce59
RDX: 0000200000000900 RSI: 00000000000089a1 RDI: 0000000000000007
RBP: 00007f1651632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1651816038 R14: 00007f1651815fa0 R15: 00007fff50466a08
 </TASK>
----------------
Code disassembly (best guess):
   0:	d1 aa 90 48 c7 c6    	shrl   $1,-0x3938b770(%rdx)
   6:	70 f7                	jo     0xffffffff
   8:	64 81 e8 73 a8 07 00 	fs sub $0x7a873,%eax
   f:	e8 de bb 07 00       	call   0x7bbf2
  14:	e9 5c fc ff ff       	jmp    0xfffffc75
  19:	e8 d4 9e c9 08       	call   0x8c99ef2
  1e:	41 f7 c4 00 02 00 00 	test   $0x200,%r12d
  25:	74 d1                	je     0xfffffff8
  27:	fb                   	sti
  28:	84 db                	test   %bl,%bl
* 2a:	75 d0                	jne    0xfffffffc <-- trapping instruction
  2c:	eb e1                	jmp    0xf
  2e:	0f 0b                	ud2
  30:	eb 88                	jmp    0xffffffba
  32:	0f 0b                	ud2
  34:	e9 f8 fe ff ff       	jmp    0xffffff31
  39:	0f 0b                	ud2
  3b:	e9 45 ff ff ff       	jmp    0xffffff85

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/29 14:59 linux-6.1.y dcbcab9d7079 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING: ODEBUG bug in handle_softirqs
* Struck through repros no longer work on HEAD.