syzbot


INFO: task hung in uhid_char_write (3)

Status: auto-obsoleted due to no activity on 2025/11/24 15:03
Subsystems: kernel
[Documentation on labels]
First crash: 227d, last: 227d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in uhid_char_write input 1 12 580d 804d 0/29 auto-obsoleted due to no activity on 2024/12/06 12:52
upstream INFO: task hung in uhid_char_write (2) kernel 1 1 398d 398d 0/29 auto-obsoleted due to no activity on 2025/06/06 08:46

Sample crash report:
INFO: task syz.4.2445:11279 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.2445      state:D stack:28472 pid:11279 tgid:11278 ppid:5855   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_timeout+0x257/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common+0x2fc/0x4e0 kernel/sched/completion.c:121
 __flush_work+0x7d7/0xcc0 kernel/workqueue.c:4244
 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4364
 uhid_dev_destroy drivers/hid/uhid.c:584 [inline]
 uhid_char_write+0xe16/0x10f0 drivers/hid/uhid.c:761
 vfs_write+0x29d/0x11d0 fs/read_write.c:684
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d3f18ebe9
RSP: 002b:00007f6d3ff43038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6d3f3b5fa0 RCX: 00007f6d3f18ebe9
RDX: 0000000000000004 RSI: 0000200000000340 RDI: 0000000000000003
RBP: 00007f6d3f211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d3f3b6038 R14: 00007f6d3f3b5fa0 R15: 00007fffbf91e428
 </TASK>

Showing all locks held in the system:
1 lock held by kthreadd/2:
4 locks held by kworker/0:0/9:
 #0: ffff888029319148 ((wq_completion)wg-kex-wg2#4){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc900000e7d10 ((work_completion)(&({ do { const void *__vpp_verify = (typeof((worker) + 0))((void *)0); (void)__vpp_verify; } while (0); ({ unsigned long __ptr; __asm__ ("" : "=r"(__ptr) : "0"((__typeof__(*((worker))) *)(( unsigned long)((worker))))); (typeof((__typeof__(*((worker))) *)(( unsigned long)((worker))))) (__ptr + (((__per_cpu_offset[(cpu)])))); }); })->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
 #2: ffff888025a69308 (&wg->static_identity.lock){++++}-{4:4}, at: wg_noise_handshake_consume_initiation+0x1c2/0x880 drivers/net/wireguard/noise.c:598
 #3: ffff888055c434c0 (&handshake->lock){++++}-{4:4}, at: wg_noise_handshake_consume_initiation+0x5ac/0x880 drivers/net/wireguard/noise.c:632
4 locks held by kworker/0:1/10:
3 locks held by kworker/u8:0/12:
3 locks held by kworker/u8:1/13:
2 locks held by kworker/1:0/24:
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c1220 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:2/36:
5 locks held by kworker/1:1/43:
3 locks held by kworker/u8:3/49:
4 locks held by kworker/u8:4/59:
3 locks held by kworker/u8:5/963:
3 locks held by kworker/0:2/976:
4 locks held by kworker/1:2/979:
4 locks held by aoe_tx0/1297:
3 locks held by kworker/u8:6/2916:
2 locks held by kworker/R-bat_e/3420:
3 locks held by kworker/u8:7/3514:
3 locks held by kworker/u8:8/3568:
3 locks held by kworker/u8:9/3587:
1 lock held by klogd/5208:
2 locks held by dhcpcd/5513:
5 locks held by dhcpcd/5514:
2 locks held by crond/5591:
2 locks held by getty/5613:
 #0: ffff88803661e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by syz-executor/5835:
1 lock held by syz-executor/5847:
3 locks held by syz-executor/5858:
5 locks held by kworker/0:3/5898:
3 locks held by kworker/0:4/5905:
2 locks held by kworker/0:5/5912:
4 locks held by kworker/1:5/5932:
3 locks held by kworker/0:6/5958:
5 locks held by kworker/1:7/5966:
2 locks held by syz.0.923/8051:
3 locks held by kworker/u8:10/9975:
1 lock held by kworker/0:7/10050:
3 locks held by kworker/0:8/10151:
1 lock held by syz.4.2375/11125:
1 lock held by syz.4.2445/11279:
 #0: ffff888047ed8068 (&uhid->devlock){+.+.}-{4:4}, at: uhid_char_write+0x6b/0x10f0 drivers/hid/uhid.c:731
6 locks held by syz.0.2448/11285:
4 locks held by kworker/u8:11/11286:
2 locks held by kworker/u8:12/11287:
3 locks held by kworker/1:9/11289:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1297 Comm: aoe_tx0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0xd/0xc0 kernel/rcu/tree.c:751
Code: 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 53 65 ff 05 e3 be 35 12 <e8> 4e 13 f3 09 48 c7 c3 a8 a2 d7 93 89 c5 83 f8 07 0f 87 82 00 00
RSP: 0018:ffffc90000a08130 EFLAGS: 00000282
RAX: 0000000000000001 RBX: ffffc90000a08d40 RCX: ffffc90000a09001
RDX: ffffc90000a08d48 RSI: ffffc90000a08d10 RDI: ffffc90000a081c8
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000003 R11: 00000000000870c9 R12: ffffc90000a08208
R13: ffffc90000a081b8 R14: ffffc90000a08d40 R15: ffffc90000a081ec
FS:  0000000000000000(0000) GS:ffff8881247b9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff34e81fd8 CR3: 0000000059e41000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_read_unlock include/linux/rcupdate.h:869 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1155 [inline]
 unwind_next_frame+0xa86/0x20a0 arch/x86/kernel/unwind_orc.c:479
 arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kmem_cache_free+0x2d1/0x4d0 mm/slub.c:4782
 kfree_skbmem+0x1a4/0x1f0 net/core/skbuff.c:1109
 __kfree_skb net/core/skbuff.c:1166 [inline]
 consume_skb net/core/skbuff.c:1397 [inline]
 consume_skb+0xcc/0x100 net/core/skbuff.c:1391
 nft_synproxy_eval_v6 net/netfilter/nft_synproxy.c:91 [inline]
 nft_synproxy_do_eval+0x943/0xd80 net/netfilter/nft_synproxy.c:145
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x2e6/0x1920 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x18a/0x340 net/netfilter/nft_chain_filter.c:161
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xbe/0x200 net/netfilter/core.c:623
 nf_hook.constprop.0+0x422/0x750 include/linux/netfilter.h:273
 NF_HOOK include/linux/netfilter.h:316 [inline]
 ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:500
 dst_input include/net/dst.h:471 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 NF_HOOK include/linux/netfilter.h:312 [inline]
 ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5991
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6104
 process_backlog+0x442/0x15e0 net/core/dev.c:6456
 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7506
 napi_poll net/core/dev.c:7569 [inline]
 net_rx_action+0xa9f/0xfe0 net/core/dev.c:7696
 handle_softirqs+0x216/0x8e0 kernel/softirq.c:579
 do_softirq kernel/softirq.c:480 [inline]
 do_softirq+0xb2/0xf0 kernel/softirq.c:467
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:910 [inline]
 __dev_queue_xmit+0xb06/0x4490 net/core/dev.c:4752
 dev_queue_xmit include/linux/netdevice.h:3361 [inline]
 tx+0xcc/0x190 drivers/block/aoe/aoenet.c:62
 kthread+0x1e1/0x3e0 drivers/block/aoe/aoecmd.c:1241
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/26 14:52 upstream fab1beda7597 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in uhid_char_write
* Struck through repros no longer work on HEAD.