Re: [syzbot] [wireguard?] BUG: workqueue lockup in wg_packet_decrypt_worker

[syzbot <syzbot+d0d2f1a65f45b319d25d@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    38872197cae2 Merge branch 'for-next/fixes' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17567005580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=56ed23170c168d4c
dashboard link: https://syzkaller.appspot.com/bug?extid=d0d2f1a65f45b319d25d
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1606a805580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c5963fdd6790/disk-38872197.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a8c2cab00c45/vmlinux-38872197.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bde15d173380/Image-38872197.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d0d2f1a65f45b319d25d@syzkaller.appspotmail.com

BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 38s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x100
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=16 refcnt=17
    in-flight: 4858:nsim_fib_event_work for 39s ,4830:nsim_fib_event_work for 40s
    pending: 3*nsim_dev_hwstats_traffic_work, 2*psi_avgs_work, vmstat_shepherd, rht_deferred_worker, free_obj_work, 3*ovs_dp_masks_rebalance, drm_fb_helper_damage_work, 2*nsim_fib_event_work
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=11 refcnt=12
    in-flight: 869:nsim_fib_event_work for 44s nsim_fib_event_work ,4806:nsim_fib_event_work for 41s nsim_fib_event_work
    pending: psi_avgs_work, 6*ovs_dp_masks_rebalance
workqueue events_unbound: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=22 refcnt=23
    in-flight: 1472:cfg80211_wiphy_work for 41s cfg80211_wiphy_work ,1438:cfg80211_wiphy_work for 43s cfg80211_wiphy_work ,1295:cfg80211_wiphy_work for 43s cfg80211_wiphy_work ,14:cfg80211_wiphy_work for 36s ,79:cfg80211_wiphy_work for 43s cfg80211_wiphy_work ,1486:cfg80211_wiphy_work for 42s cfg80211_wiphy_work ,12:cfg80211_wiphy_work for 39s
    pending: 2*cfg80211_wiphy_work, nsim_dev_trap_report_work, toggle_allocation_gate, macvlan_process_broadcast, 3*nsim_dev_trap_report_work, flush_memcg_stats_dwork, macvlan_process_broadcast
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=7 refcnt=8
    in-flight: 1234:cfg80211_wiphy_work for 43s cfg80211_wiphy_work
    pending: macvlan_process_broadcast, crng_reseed, 3*macvlan_process_broadcast
workqueue events_power_efficient: flags=0x82
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=5 refcnt=6
    in-flight: 50:neigh_periodic_work for 33s
    pending: neigh_managed_work, fb_flashcursor, wg_ratelimiter_gc_entries, neigh_managed_work
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    pending: neigh_periodic_work, do_cache_clean
workqueue events_dfl_long: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=9 refcnt=10
    pending: 9*defense_work_handler
workqueue netns: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=4
    in-flight: 1183:cleanup_net for 45s
workqueue mm_percpu_wq: flags=0x108
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
workqueue mld: flags=0x40108
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=73
    pending: mld_ifc_work
    inactive: 2*mld_ifc_work, mld_dad_work, mld_ifc_work, mld_dad_work, mld_ifc_work, mld_dad_work, 4*mld_ifc_work, 2*mld_dad_work, mld_ifc_work, mld_dad_work, 3*mld_ifc_work, 2*mld_dad_work, 5*mld_ifc_work, mld_dad_work, mld_ifc_work, mld_dad_work, 3*mld_ifc_work, 3*mld_dad_work, mld_ifc_work, 2*mld_dad_work, 3*mld_ifc_work, mld_dad_work, 2*mld_ifc_work, mld_dad_work, 6*mld_ifc_work, mld_dad_work, mld_ifc_work, 2*mld_dad_work, 3*mld_ifc_work, 2*mld_dad_work, mld_ifc_work, 2*mld_dad_work, mld_ifc_work, 8*mld_dad_work
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=95
    pending: mld_ifc_work
    inactive: mld_ifc_work, mld_dad_work, mld_ifc_work, mld_dad_work, 9*mld_ifc_work, 2*mld_dad_work, 6*mld_ifc_work, mld_dad_work, 4*mld_ifc_work, mld_dad_work, 4*mld_ifc_work, 62*mld_dad_work
workqueue ipv6_addrconf: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=178 MAYDAY
    in-flight: 2825(RESCUER):addrconf_dad_work for 0s
    pending: mayday_cursor_func
    inactive: 172*addrconf_dad_work
workqueue bat_events: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=51 MAYDAY
    in-flight: 2857(RESCUER):batadv_tt_purge for 11s
    pending: mayday_cursor_func
    inactive: 4*batadv_tt_purge, batadv_dat_purge, batadv_bla_periodic_work, 6*batadv_mcast_mla_update, 5*batadv_iv_send_outstanding_bat_ogm_packet, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, 5*batadv_iv_send_outstanding_bat_ogm_packet, 6*batadv_purge_orig, 6*batadv_iv_send_outstanding_bat_ogm_packet, batadv_tt_purge
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_decrypt_worker, wg_packet_encrypt_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=4 refcnt=5
    in-flight: 9:wg_packet_decrypt_worker for 40s wg_packet_decrypt_worker
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_decrypt_worker, wg_packet_tx_worker, wg_packet_encrypt_worker
workqueue wg-kex-wg2: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=4 refcnt=5
    in-flight: 10:wg_packet_decrypt_worker for 41s wg_packet_decrypt_worker
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  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-kex-wg0: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_decrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg1: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-kex-wg1: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    in-flight: 1115:wg_packet_decrypt_worker for 41s wg_packet_decrypt_worker
    pending: wg_packet_encrypt_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4356:wg_packet_handshake_receive_worker for 41s
workqueue wg-kex-wg2: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    pending: 2*wg_packet_handshake_send_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_tx_worker
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    pending: 2*wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  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-kex-wg1: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_decrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 2: cpus=0 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=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  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-kex-wg0: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_tx_worker, wg_packet_encrypt_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_tx_worker
workqueue wg-kex-wg1: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_decrypt_worker, wg_packet_encrypt_worker, wg_packet_tx_worker
  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-kex-wg2: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    in-flight: 40:wg_packet_handshake_send_worker for 6s
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_tx_worker, wg_packet_encrypt_worker
pool 2: cpus=0 node=0 flags=0x0 nice=0 hung=38s workers=8 idle: 5002 4997
pool 6: cpus=1 node=0 flags=0x0 nice=0 hung=21s workers=7 idle: 26 24 4967 5000 4999
pool 8: cpus=0-1 flags=0x6 nice=0 hung=0s workers=12 manager: 5001
Showing backtraces of busy workers in stalled worker pools:
pool 2:
task:kworker/0:1     state:R  running task     stack:0     pid:10    tgid:10    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:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7456
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7480
 __kunmap_atomic include/linux/highmem-internal.h:247 [inline]
 sg_miter_stop+0x220/0x2cc lib/scatterlist.c:941
 chacha20poly1305_crypt_sg_inplace+0x75c/0xc30 lib/crypto/chacha20poly1305.c:319
 chacha20poly1305_decrypt_sg_inplace+0x6c/0x94 lib/crypto/chacha20poly1305.c:353
 decrypt_packet drivers/net/wireguard/receive.c:278 [inline]
 wg_packet_decrypt_worker+0x490/0xa00 drivers/net/wireguard/receive.c:501
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3479
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3560
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 2:
task:kworker/0:5     state:R  running task     stack:0     pid:4858  tgid:4858  ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: events nsim_fib_event_work
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 __schedule_loop kernel/sched/core.c:7354 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7369
 schedule_timeout+0x13c/0x28c kernel/time/sleep_timeout.c:99
 schedule_timeout_uninterruptible+0x78/0xbc kernel/time/sleep_timeout.c:158
 msleep+0x3c/0x68 kernel/time/sleep_timeout.c:318
 nsim_fib6_rt_add drivers/net/netdevsim/fib.c:693 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:759 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
 nsim_fib_event+0x57a0/0x60c4 drivers/net/netdevsim/fib.c:889
 nsim_fib_event_work+0x1d8/0x320 drivers/net/netdevsim/fib.c:1493
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3479
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3560
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 2:
task:kworker/0:4     state:R  running task     stack:0     pid:4830  tgid:4830  ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: events nsim_fib_event_work
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7456
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7480
 irq_work_queue+0xa0/0xa4 kernel/irq_work.c:125
 __rhashtable_insert_fast include/linux/rhashtable.h:852 [inline]
 rhashtable_insert_fast include/linux/rhashtable.h:886 [inline]
 nsim_fib6_rt_add drivers/net/netdevsim/fib.c:686 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:759 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
 nsim_fib_event+0x4f5c/0x60c4 drivers/net/netdevsim/fib.c:889
 nsim_fib_event_work+0x1d8/0x320 drivers/net/netdevsim/fib.c:1493
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3479
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3560
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 2:
task:kworker/0:3     state:R  running task     stack:0     pid:4356  tgid:4356  ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: wg-kex-wg2 wg_packet_handshake_receive_worker
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7456
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7480
 __local_bh_enable_ip+0x20c/0x35c kernel/softirq.c:480
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:923 [inline]
 mod_peer_timer+0x21c/0x25c drivers/net/wireguard/timers.c:38
 wg_timers_session_derived+0x5c/0x6c drivers/net/wireguard/timers.c:208
 wg_receive_handshake_packet drivers/net/wireguard/receive.c:178 [inline]
 wg_packet_handshake_receive_worker+0x5b8/0xcf8 drivers/net/wireguard/receive.c:213
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3479
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3560
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 2:
task:kworker/0:0     state:R  running task     stack:0     pid:9     tgid:9     ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue: wg-crypt-wg1 wg_packet_decrypt_worker
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7277
 preempt_schedule_common+0xd4/0x190 kernel/sched/core.c:7456
 preempt_schedule+0x60/0x78 kernel/sched/core.c:7480
 __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:3396 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3479
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3560
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
pool 2:


---
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