BUG: workqueue lockup in wg_packet_decrypt_worker

Status: moderation: reported on 2026/09/13 23:41
Subsystems: wireguard
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+7e0f973511fe5c0c51b3@syzkaller.appspotmail.com
First crash: 4d05h, last: 8h02m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
83add95e assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ✅ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ BUG: workqueue lockup in wg_packet_decrypt_worker 2026/09/11 01:03 2026/09/11 01:03 2026/09/11 01:41 1fe56c0a

Sample crash report:
BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 32s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x100
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=15 refcnt=16
    in-flight: 4304:reg_todo for 92s
    pending: 6*nsim_dev_hwstats_traffic_work, 2*ovs_dp_masks_rebalance, psi_avgs_work, bpf_prog_free_deferred, free_obj_work, 3*psi_avgs_work
workqueue events_unbound: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=17 refcnt=18
    in-flight: 7827:nsim_dev_trap_report_work for 1s ,1150:nsim_dev_trap_report_work for 1s ,2630:nsim_dev_trap_report_work for 2s ,12:cfg80211_wiphy_work for 68s cfg80211_wiphy_work ,1168:cfg80211_wiphy_work for 90s cfg80211_wiphy_work ,40:cfg80211_wiphy_work for 93s cfg80211_wiphy_work ,4988:nsim_dev_trap_report_work for 0s
    pending: 5*nsim_dev_trap_report_work, toggle_allocation_gate, nsim_dev_trap_report_work
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=3 refcnt=4
    in-flight: 4990:linkwatch_event for 95s ,13:cfg80211_wiphy_work for 83s cfg80211_wiphy_work
workqueue events_power_efficient: flags=0x82
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=4 refcnt=5
    in-flight: 62:neigh_periodic_work for 51s ,7826:gc_worker for 10s
    pending: wg_ratelimiter_gc_entries, fb_flashcursor
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    in-flight: 4865:reg_check_chans_work for 31s ,54:crda_timeout_work for 86s
workqueue events_dfl_long: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=6 refcnt=7
    pending: 6*defense_work_handler
workqueue netns: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=4
    in-flight: 4989:cleanup_net for 103s
workqueue mm_percpu_wq: flags=0x108
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
workqueue ipv6_addrconf: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=8 MAYDAY
    in-flight: 2820(RESCUER):addrconf_verify_work for 23s
    inactive: 2*addrconf_verify_work
workqueue bat_events: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=50 MAYDAY
    in-flight: 2852(RESCUER):batadv_dat_purge for 6s
    inactive: batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_mcast_mla_update, batadv_tt_purge, batadv_dat_purge, batadv_bla_periodic_work, batadv_mcast_mla_update, batadv_tt_purge, batadv_mcast_mla_update, batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, 3*batadv_iv_send_outstanding_bat_ogm_packet, batadv_bla_periodic_work, batadv_dat_purge, 3*batadv_iv_send_outstanding_bat_ogm_packet, 2*batadv_mcast_mla_update, 6*batadv_iv_send_outstanding_bat_ogm_packet, 2*batadv_purge_orig, 2*batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, 3*batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, batadv_iv_send_outstanding_bat_ogm_packet, batadv_tt_purge, batadv_iv_send_outstanding_bat_ogm_packet, batadv_dat_purge, batadv_bla_periodic_work, 2*batadv_tt_purge
workqueue wg-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    in-flight: 4893:wg_packet_encrypt_worker for 36s
    pending: wg_packet_encrypt_worker
workqueue wg-kex-wg1: flags=0x124
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_decrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4806:wg_packet_tx_worker for 5s
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_decrypt_worker, wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue hci2: flags=0x20012
  pwq 9: cpus=0-1 node=0 flags=0x4 nice=-20 active=1 refcnt=4
    in-flight: 4718:hci_cmd_sync_work for 13s
workqueue hci0: flags=0x20012
  pwq 9: cpus=0-1 node=0 flags=0x4 nice=-20 active=1 refcnt=4
    pending: hci_cmd_timeout
workqueue hci0: flags=0x20012
  pwq 9: cpus=0-1 node=0 flags=0x4 nice=-20 active=1 refcnt=4
    in-flight: 4706:hci_cmd_sync_work for 2s
workqueue wg-kex-wg0: flags=0x124
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4790:wg_packet_handshake_receive_worker for 1s
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    in-flight: 4803:wg_packet_decrypt_worker for 37s wg_packet_decrypt_worker
    pending: wg_packet_encrypt_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_tx_worker, wg_packet_encrypt_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_tx_worker, wg_packet_encrypt_worker, wg_packet_decrypt_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_tx_worker, wg_packet_encrypt_worker, wg_packet_decrypt_worker
workqueue krds_cp_wq#0/0: flags=0x20002
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=4
    pending: rds_connect_worker
pool 2: cpus=0 node=0 flags=0x0 nice=0 hung=0s workers=9 idle: 4797 4820 10 4987 1149 4805 9
pool 6: cpus=1 node=0 flags=0x0 nice=0 hung=32s workers=9 idle: 24 6392 7740 26 865 4811
pool 8: cpus=0-1 flags=0x6 nice=0 hung=0s workers=15 manager: 7828
pool 9: cpus=0-1 node=0 flags=0x4 nice=-20 hung=0s workers=7 idle: 4705 50 4712 4715 4714
Showing backtraces of busy workers in stalled worker pools:
pool 6:
task:kworker/1:4     state:R  running task     stack:0     pid:4803  tgid:4803  ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: wg-crypt-wg2 wg_packet_decrypt_worker
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5520 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7270
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7449
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7473
 __local_bh_enable_ip+0x20c/0x35c kernel/softirq.c:480
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x3c/0x4c kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 ptr_ring_consume_bh include/linux/ptr_ring.h:399 [inline]
 wg_packet_decrypt_worker+0x980/0xa00 drivers/net/wireguard/receive.c:499
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3470
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3551
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 6:
task:kworker/1:6     state:R  running task     stack:0     pid:4893  tgid:4893  ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: wg-crypt-wg0 wg_packet_encrypt_worker
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5520 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7270
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7449
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7473
 __local_bh_enable_ip+0x20c/0x35c kernel/softirq.c:480
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x3c/0x4c kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 ptr_ring_consume_bh include/linux/ptr_ring.h:399 [inline]
 wg_packet_encrypt_worker+0x25c/0x1290 drivers/net/wireguard/send.c:293
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3470
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3551
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 21:01 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in wg_packet_decrypt_worker
2026/09/12 05:17 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in wg_packet_decrypt_worker
2026/09/09 23:59 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in wg_packet_decrypt_worker
2026/09/09 23:35 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in wg_packet_decrypt_worker
* Struck through repros no longer work on HEAD.