syzbot


INFO: rcu detected stall in kcm_release

Status: auto-obsoleted due to no activity on 2026/06/17 07:13
Subsystems: net
Labels: prio:high
[Documentation on labels]
First crash: 94d, last: 94d
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
6fb9eaad-ae94-4798-a81b-6083020197fc assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: rcu detected stall in kcm_release 2026/05/31 11:17 2026/05/31 11:17 2026/05/31 12:15 6b4a844333e83556da95d61d7f207e7ef5cd4bc6

			
		
783a4b52-8eb6-48ad-a6b8-e6ae63d3ba5b assessment-security 💥 INFO: rcu detected stall in kcm_release 2026/05/14 16:29 2026/05/14 16:29 2026/05/14 16:30 6ccb967e465e832a7bfd7a116ad00d52a0923a5d
failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128
From /app/workdir/repo/linux
 * branch                HEAD       -> FETCH_HEAD
Updating files:  ...
truncated to first 200 bytes; open job for full error

Sample crash report:
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P12657/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=78037, q=940 ncpus=1)
task:syz.0.1543      state:R  running task     stack:23432 pid:12657 tgid:12652 ppid:5824   task_flags:0x40054c flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:81 [inline]
RIP: 0010:__orc_find+0x70/0xf0 arch/x86/kernel/unwind_orc.c:103
Code: ec 72 4e 4c 89 e2 48 29 ea 48 89 d6 48 c1 ea 3f 48 c1 fe 02 48 01 f2 48 d1 fa 48 8d 5c 95 00 48 89 da 48 c1 ea 03 0f b6 34 0a <48> 89 da 83 e2 07 83 c2 03 40 38 f2 7c 05 40 84 f6 75 4b 48 63 13
RSP: 0018:ffffc90004d1f218 EFLAGS: 00000a02
RAX: ffffffff92088878 RBX: ffffffff91520880 RCX: dffffc0000000000
RDX: 1ffffffff22a4110 RSI: 0000000000000000 RDI: ffffffff91520874
RBP: ffffffff91520874 R08: ffffffff920888d2 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000085867 R12: ffffffff9152088c
R13: ffffffff89586751 R14: ffffffff91520874 R15: ffffffff91520874
 orc_find arch/x86/kernel/unwind_orc.c:238 [inline]
 unwind_next_frame+0x2ec/0x1ea0 arch/x86/kernel/unwind_orc.c:510
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 free_to_pcs_bulk+0x255/0x8e0 mm/slub.c:5986
 kfree_skb_add_bulk net/core/skbuff.c:1280 [inline]
 kfree_skb_list_reason+0x344/0x4b0 net/core/skbuff.c:1298
 skb_release_data+0x78e/0x9d0 net/core/skbuff.c:1126
 skb_release_all net/core/skbuff.c:1203 [inline]
 __kfree_skb net/core/skbuff.c:1217 [inline]
 sk_skb_reason_drop+0x102/0x1b0 net/core/skbuff.c:1255
 kfree_skb_reason include/linux/skbuff.h:1322 [inline]
 kfree_skb include/linux/skbuff.h:1331 [inline]
 kcm_release+0x178/0x740 net/kcm/kcmsock.c:1697
 __sock_release+0xb3/0x260 net/socket.c:662
 sock_close+0x1c/0x30 net/socket.c:1455
 __fput+0x3ff/0xb40 fs/file_table.c:469
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x8b8/0x2b60 kernel/exit.c:976
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1118
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x668/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f87cf59c799
RSP: 002b:00007f87d0467028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: 0000000004380000 RBX: 00007f87cf816090 RCX: 00007f87cf59c799
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000001
RBP: 00007f87cf632c99 R08: 0000000000000000 R09: 0000000000000000
R10: 000000007ffff000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f87cf816128 R14: 00007f87cf816090 R15: 00007fff30a01ba8
 </TASK>
net_ratelimit: 16232 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
net_ratelimit: 11533 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:4f:93:58:e4:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/19 07:08 upstream 8a30aeb0d1b4 0199f9a1 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in kcm_release
* Struck through repros no longer work on HEAD.