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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: 2d08h, last: 1d08h
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 767d 763d 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 904d 900d 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 810d 805d 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 1492d 1466d 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 1996d 2016d 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 1018d 1018d 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 663d 688d 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 462d 462d 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 353d 353d 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 1929d 1890d 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 104d 156d 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 0xffff88811a3bd700 of 8 bytes by task 3396 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+0x5f/0x310 net/core/dev.c:7678
 napi_threaded_poll_loop+0x1b9/0x630 net/core/dev.c:7797
 napi_threaded_poll+0x15f/0x1f0 net/core/dev.c:7848
 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 0xffff88811a3bd700 of 8 bytes by task 3385 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+0x4cd/0x9d0 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: 0x0000000000000294 -> 0x00000000000002b4

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3385 Comm: kworker/0:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Workqueue: wg-kex-wg1 wg_packet_handshake_receive_worker
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.