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KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (12)

Status: moderation: reported on 2026/02/12 13:42
Subsystems: wireguard
[Documentation on labels]
Reported-by: syzbot+e66eacb9b49734684ec9@syzkaller.appspotmail.com
First crash: 23d, last: 3d14h
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
6f68bf46-10ff-45d9-aa78-a7a3de2bdf63 repro KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (12) 2026/03/06 03:03 2026/03/06 03:03 2026/03/06 03:06 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
a328be70-8dda-40e8-a092-17b53eab7d68 assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (12) 2026/02/24 16:09 2026/02/24 16:09 2026/02/24 16:13 305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9
3b1f1a3e-8107-4a2b-9616-ee768608cf4b assessment-kcsan 💥 KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (12) 2026/02/12 16:24 2026/02/13 12:42 2026/02/13 12:47 3f45136dc7eb71e0f74e923b9f5ca8ecd555f59a fork/exec ./syz-agent: no such file or directory
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (7) wireguard 6 1 788d 785d 0/29 auto-obsoleted due to no activity on 2024/02/12 20:57
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (5) wireguard 6 2 925d 921d 0/29 auto-obsoleted due to no activity on 2023/09/29 02:04
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (6) wireguard 6 3 831d 826d 0/29 auto-obsoleted due to no activity on 2024/01/01 00:52
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (3) wireguard 6 2 1513d 1488d 0/29 auto-closed as invalid on 2022/02/22 09:23
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll wireguard 6 3 2017d 2037d 0/29 auto-closed as invalid on 2020/10/01 18:48
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (4) wireguard 6 1 1039d 1039d 0/29 auto-obsoleted due to no activity on 2023/06/06 16:15
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (8) wireguard 6 2 684d 709d 0/29 auto-obsoleted due to no activity on 2024/05/26 12:41
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (9) wireguard 6 1 484d 484d 0/29 auto-obsoleted due to no activity on 2025/01/03 07:26
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (10) wireguard 6 1 374d 374d 0/29 auto-obsoleted due to no activity on 2025/04/22 20:01
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (2) wireguard 6 1 1950d 1912d 0/29 auto-closed as invalid on 2020/12/25 11:24
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (11) wireguard 6 2 125d 177d 0/29 auto-obsoleted due to no activity on 2025/12/27 15:42

Sample crash report:
==================================================================
BUG: KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll

read-write to 0xffff88811ae86a50 of 8 bytes by task 5251 on cpu 1:
 update_rx_stats drivers/net/wireguard/receive.c:23 [inline]
 wg_packet_consume_data_done drivers/net/wireguard/receive.c:358 [inline]
 wg_packet_rx_poll+0xed7/0x10f0 drivers/net/wireguard/receive.c:474
 __napi_poll+0x61/0x330 net/core/dev.c:7695
 napi_threaded_poll_loop+0x1b9/0x630 net/core/dev.c:7814
 napi_threaded_poll+0x15f/0x1f0 net/core/dev.c:7865
 kthread+0x22a/0x280 kernel/kthread.c:467
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff88811ae86a50 of 8 bytes by task 24016 on cpu 0:
 update_rx_stats drivers/net/wireguard/receive.c:23 [inline]
 wg_receive_handshake_packet drivers/net/wireguard/receive.c:198 [inline]
 wg_packet_handshake_receive_worker+0x49f/0x5d0 drivers/net/wireguard/receive.c:213
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0x4de/0x9e0 kernel/workqueue.c:3358
 worker_thread+0x581/0x770 kernel/workqueue.c:3439
 kthread+0x22a/0x280 kernel/kthread.c:467
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000234 -> 0x0000000000000254

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 24016 Comm: kworker/0:1 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: wg-kex-wg1 wg_packet_handshake_receive_worker
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/03 21:00 upstream af4e9ef3d784 4180d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll
2026/02/23 12:45 upstream 6de23f81a5e0 6beca497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll
2026/02/17 14:18 upstream 970296997869 e439b951 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll
2026/02/12 18:59 upstream 37a93dd5c49b 504cb1bf .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll
2026/02/11 19:17 upstream 192c0159402e 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll
* Struck through repros no longer work on HEAD.