KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (13)

Status: moderation: reported on 2026/10/28 11:48
Subsystems: wireguard
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+186ed8409670b81a5b45@syzkaller.appspotmail.com
First crash: 5d18h, last: 1d05h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
c7ae4ddc assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ FuzzingArtifact: ❌ MemoryCorruption: ❌ NetworkNeedsSetup: ✅ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (13) 2026/10/26 00:01 2026/10/26 00:01 2026/10/26 00:45 1d9ca40b
a42ed69b assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (13) 2026/10/24 12:39 2026/10/24 12:39 2026/10/24 13:04 1d9ca40b
▶ ▼ Similar bugs (12)
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 1025d 1021d 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 (12) prio:low wireguard 6 20 75d 259d 0/29 auto-obsoleted due to no activity on 2026/10/10 09:34
upstream KCSAN: data-race in wg_packet_handshake_receive_worker / wg_packet_rx_poll (5) wireguard 6 2 1162d 1158d 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 1068d 1063d 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 1750d 1724d 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 2254d 2274d 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 1276d 1276d 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 921d 946d 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 720d 720d 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 611d 611d 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 2187d 2148d 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 362d 414d 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 0xffff888124911020 of 8 bytes by task 13937 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+0x456/0x570 drivers/net/wireguard/receive.c:213
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0x53f/0xa20 kernel/workqueue.c:3578
 worker_thread+0x56c/0x770 kernel/workqueue.c:3659
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff888124911020 of 8 bytes by task 9183 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+0xe69/0x1090 drivers/net/wireguard/receive.c:474
 __napi_poll+0x61/0x300 net/core/dev.c:7938
 napi_threaded_poll_loop+0x1e9/0x6c0 net/core/dev.c:8058
 napi_threaded_poll+0x193/0x240 net/core/dev.c:8113
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000000000001f4 -> 0x0000000000000288

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9183 Comm: napi/wg1-0 Tainted: G        W          Y syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN, [Y]=FORCED_BIND
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/29 00:56 upstream c339f4010dea 858db2ec .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
2026/10/24 11:38 upstream 5b0764a53235 1d9ca40b .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.