From syzbot+9ca7674fa7521a3f1bc2 at syzkaller.appspotmail.com  Mon Jun  1 14:33:31 2026
From: syzbot+9ca7674fa7521a3f1bc2 at syzkaller.appspotmail.com (syzbot)
Date: Mon, 01 Jun 2026 07:33:31 -0700
Subject: [syzbot] [wireguard?] KCSAN: data-race in wg_socket_send_skb_to_peer
 / wg_socket_send_skb_to_peer (9)
Message-ID: <6a1d983b.b111c304.35cd64.0028.GAE@google.com>

Hello,

syzbot found the following issue on:

HEAD commit:    9215e74f228f Merge tag 'block-7.1-20260529' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10465ef2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f571f22917457cd8
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca7674fa7521a3f1bc2
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1ddf3069118d/disk-9215e74f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0913e4ffbdb8/vmlinux-9215e74f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3fe3943ae796/bzImage-9215e74f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca7674fa7521a3f1bc2 at syzkaller.appspotmail.com

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

read-write to 0xffff88811af99028 of 8 bytes by task 310 on cpu 1:
 wg_socket_send_skb_to_peer+0xe8/0x130 drivers/net/wireguard/socket.c:182
 wg_socket_send_buffer_to_peer+0xf1/0x120 drivers/net/wireguard/socket.c:199
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x10d/0x160 drivers/net/wireguard/send.c:51
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 kthread+0x22a/0x280 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 0xffff88811af99028 of 8 bytes by task 15360 on cpu 0:
 wg_socket_send_skb_to_peer+0xe8/0x130 drivers/net/wireguard/socket.c:182
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x12d/0x330 drivers/net/wireguard/send.c:276
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 kthread+0x22a/0x280 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: 0x0000000000000a2c -> 0x0000000000000ac0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15360 Comm: kworker/0:2 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: wg-crypt-wg2 wg_packet_tx_worker
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller at googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup