[syzbot] [wireguard?] KCSAN: data-race in wg_packet_encrypt_worker / wg_packet_encrypt_worker

[syzbot <syzbot+75273239c9ffd7dc304f@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0f23d56f17fd Merge tag 'linux_kselftest-next-7.3-rc1' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c9b679580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e688dbf432017c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=75273239c9ffd7dc304f
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a243b05cdc37/disk-0f23d56f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3af864b2bf56/vmlinux-0f23d56f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c3f9cd19ac5/bzImage-0f23d56f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+75273239c9ffd7dc304f@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in wg_packet_encrypt_worker / wg_packet_encrypt_worker

read to 0xffff88811ac90080 of 4 bytes by task 3410 on cpu 0:
 wg_cpumask_choose_online drivers/net/wireguard/queueing.h:107 [inline]
 wg_queue_enqueue_per_peer_tx drivers/net/wireguard/queueing.h:183 [inline]
 wg_packet_encrypt_worker+0x9f5/0xe90 drivers/net/wireguard/send.c:305
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 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

write to 0xffff88811ac90080 of 4 bytes by task 15243 on cpu 1:
 wg_cpumask_choose_online drivers/net/wireguard/queueing.h:110 [inline]
 wg_queue_enqueue_per_peer_tx drivers/net/wireguard/queueing.h:183 [inline]
 wg_packet_encrypt_worker+0xcca/0xe90 drivers/net/wireguard/send.c:305
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 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: 0x00000002 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15243 Comm: kworker/1:19 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: wg-crypt-wg0 wg_packet_encrypt_worker
==================================================================


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