BUG: soft lockup in wg_packet_handshake_send_worker

Status: moderation: reported on 2026/10/22 04:46
Subsystems: wireguard
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+27fd4111ee7a5c84ce5b@syzkaller.appspotmail.com
First crash: 4d05h, last: 4d05h
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ID Workflow Result Correct Bug Created Started Finished Revision
06abf703 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ BUG: soft lockup in wg_packet_handshake_send_worker 2026/10/20 00:04 2026/10/20 00:04 2026/10/20 00:51 e931f328
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 BUG: soft lockup in wg_packet_handshake_send_worker 1 2 1190d 1196d 0/2 auto-obsoleted due to no activity on 2023/10/18 09:06
linux-5.15 BUG: soft lockup in wg_packet_handshake_send_worker 1 2 681d 705d 0/3 auto-obsoleted due to no activity on 2025/03/20 05:34
android-5-10 BUG: soft lockup in wg_packet_handshake_send_worker 1 6 1162d 1202d 0/2 auto-obsoleted due to no activity on 2023/11/15 02:30
linux-5.15 INFO: rcu detected stall in wg_packet_handshake_send_worker (2) 1 1 346d 346d 0/3 auto-obsoleted due to no activity on 2026/02/18 00:47
upstream INFO: rcu detected stall in wg_packet_handshake_send_worker (6) crypto 1 1 548d 548d 0/29 auto-obsoleted due to no activity on 2025/07/21 04:05
upstream INFO: rcu detected stall in wg_packet_handshake_send_worker (4) wireguard 1 1 1192d 1192d 0/29 auto-obsoleted due to no activity on 2023/10/15 22:40
linux-5.15 INFO: rcu detected stall in wg_packet_handshake_send_worker 1 1 927d 927d 0/3 auto-obsoleted due to no activity on 2024/07/16 21:11
upstream INFO: rcu detected stall in wg_packet_handshake_send_worker (5) wireguard 1 1 1056d 1055d 0/29 auto-obsoleted due to no activity on 2024/02/29 10:43
upstream INFO: rcu detected stall in wg_packet_handshake_send_worker (3) kernel 1 1 1401d 1401d 0/29 auto-obsoleted due to no activity on 2023/04/12 00:54
linux-6.1 INFO: rcu detected stall in wg_packet_handshake_send_worker 1 1 873d 873d 0/3 auto-obsoleted due to no activity on 2024/09/09 01:47

Sample crash report:
watchdog: BUG: soft lockup - CPU#0 stuck for 21s! [kworker/u8:1:4838]
Modules linked in:
irq event stamp: 459152
hardirqs last  enabled at (459151): [<ffff800081f2b350>] crng_make_state+0x288/0x4f8 drivers/char/random.c:383
hardirqs last disabled at (459152): [<ffff8000859e1368>] __el1_irq arch/arm64/kernel/entry-common.c:527 [inline]
hardirqs last disabled at (459152): [<ffff8000859e1368>] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:543
softirqs last  enabled at (459112): [<ffff80008023bd84>] softirq_handle_end kernel/softirq.c:491 [inline]
softirqs last  enabled at (459112): [<ffff80008023bd84>] handle_softirqs+0xa98/0x1054 kernel/softirq.c:673
softirqs last disabled at (458535): [<ffff8000800103d4>] __do_softirq+0x14/0x20 kernel/softirq.c:679
CPU: 0 UID: 0 PID: 4838 Comm: kworker/u8:1 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: linux,dummy-virt (DT)
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : bytes_is_nonzero mm/kasan/generic.c:97 [inline]
pc : memory_is_nonzero mm/kasan/generic.c:115 [inline]
pc : memory_is_poisoned_n mm/kasan/generic.c:140 [inline]
pc : memory_is_poisoned mm/kasan/generic.c:172 [inline]
pc : check_region_inline mm/kasan/generic.c:191 [inline]
pc : kasan_check_range+0x114/0x1a8 mm/kasan/generic.c:200
lr : __asan_memcpy+0x3c/0xa0 mm/kasan/shadow.c:105
sp : ffff8000a04b7010
x29: ffff8000a04b7010 x28: 00066424111da257 x27: ffff8000a04b761d
x26: 00053f83f009c722 x25: 0002549094960241 x24: 00064aa6a86400b9
x23: 0005960e83c02e3a x22: ffff8000a04b71a0 x21: ffff8000a04b7398
x20: ffff8000816ccd08 x19: 0000000000000028 x18: 0006452e4349f51d
x17: 00065df6bb292e57 x16: 0000034ee642473b x15: 00023c19029745f0
x14: 000566cff0a2f81b x13: 00032332937c852e x12: ffff700014096e78
x11: 1ffff00014096e77 x10: ffff700014096e77 x9 : dfff800000000000
x8 : ffff8000a04b73bf x7 : 0000000000000005 x6 : ffff700014096e73
x5 : ffff8000a04b7398 x4 : ffff700014096e73 x3 : ffff8000816ccd08
x2 : 0000000000000000 x1 : 0000000000000028 x0 : 0000000000000001
Call trace:
 kasan_check_range+0x114/0x1a8 mm/kasan/generic.c:201 (P)
 fdifference lib/crypto/curve25519-hacl64.c:357 [inline]
 addanddouble_fmonty lib/crypto/curve25519-hacl64.c:502 [inline]
 ladder_smallloop_cmult_small_loop_step lib/crypto/curve25519-hacl64.c:550 [inline]
 ladder_smallloop_cmult_small_loop_double_step lib/crypto/curve25519-hacl64.c:560 [inline]
 ladder_smallloop_cmult_small_loop lib/crypto/curve25519-hacl64.c:570 [inline]
 ladder_bigloop_cmult_big_loop lib/crypto/curve25519-hacl64.c:583 [inline]
 ladder_cmult.constprop.0+0x408/0x3290 lib/crypto/curve25519-hacl64.c:597
 curve25519_generic+0x2b8/0x3af0 lib/crypto/curve25519-hacl64.c:779
 curve25519_base_arch lib/crypto/curve25519.c:35 [inline]
 curve25519_generate_public+0x48/0x9c lib/crypto/curve25519.c:57
 wg_noise_handshake_create_initiation+0x1e0/0x4e0 drivers/net/wireguard/noise.c:542
 wg_packet_send_handshake_initiation+0x154/0x288 drivers/net/wireguard/send.c:34
 wg_packet_handshake_send_worker+0x1c/0x3c drivers/net/wireguard/send.c:51
 process_one_work+0x830/0x1c00 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x42c/0xc90 kernel/workqueue.c:3560
 kthread+0x2ec/0x384 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:854
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 3828 Comm: kworker/u8:4 Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: linux,dummy-virt (DT)
Workqueue: events_unbound nsim_dev_trap_report_work
pstate: 10000005 (nzcV daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : arch_local_irq_restore arch/arm64/include/asm/irqflags.h:197 [inline]
pc : lock_acquire kernel/locking/lockdep.c:5946 [inline]
pc : lock_acquire+0x428/0x478 kernel/locking/lockdep.c:5899
lr : lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline]
lr : lock_acquire kernel/locking/lockdep.c:5945 [inline]
lr : lock_acquire+0x408/0x478 kernel/locking/lockdep.c:5899
sp : ffff8000a2927920
x29: ffff8000a2927980 x28: ffff8000882e7ee0 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000000 x24: ffff800085554448
x23: 0000000000000001 x22: ffff800088284308 x21: 0000000000000001
x20: 0000000000000000 x19: ffff000010d8b258 x18: 0000000000000000
x17: 1ffff0001109f44a x16: 1fffe00001f24b8b x15: ffff8000882ea998
x14: 1ffff0001105d533 x13: 0000000000000000 x12: 0000000000008000
x11: ffff800088283000 x10: 0000000000000050 x9 : 000000000000066d
x8 : ffff00000f9257c0 x7 : 0000000047000000 x6 : 0000000000000670
x5 : 0000000000000004 x4 : 000000004ae08fde x3 : 1fffe00001f24af9
x2 : 0000000000000000 x1 : ffff7fffe3bb6000 x0 : 00000000000000c0
Call trace:
 __daif_local_irq_restore arch/arm64/include/asm/irqflags.h:175 [inline] (P)
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:195 [inline] (P)
 lock_acquire kernel/locking/lockdep.c:5946 [inline] (P)
 lock_acquire+0x428/0x478 kernel/locking/lockdep.c:5899 (P)
 _mutex_trylock_nest_lock+0x128/0x160 kernel/locking/mutex.c:1230
 devl_trylock+0x18/0x30 net/devlink/core.c:320
 nsim_dev_trap_report_work+0x3c/0xaa0 drivers/net/netdevsim/dev.c:834
 process_one_work+0x830/0x1c00 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x42c/0xc90 kernel/workqueue.c:3560
 kthread+0x2ec/0x384 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:854

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/18 04:41 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master 58161ead29e5 432c0077 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm64 BUG: soft lockup in wg_packet_handshake_send_worker
* Struck through repros no longer work on HEAD.