[moderation] [wireguard?] KCSAN: data-race in wg_index_hashtable_insert / wg_index_hashtable_lookup (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3609fa95fb0f Merge tag 'devicetree-fixes-for-6.19-2' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=101ff69a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b319ff1b6a2797ca
dashboard link: https://syzkaller.appspot.com/bug?extid=1ba01f5dd6b508ce408b
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [Ja...@zx2c4.com andrew...@lunn.ch da...@davemloft.net edum...@google.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com wire...@lists.zx2c4.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3018b7ea95aa/disk-3609fa95.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b7f25f6e87af/vmlinux-3609fa95.xz
kernel image: https://storage.googleapis.com/syzbot-assets/13d7f9c6c13e/bzImage-3609fa95.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ba01f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in wg_index_hashtable_insert / wg_index_hashtable_lookup

write to 0xffff888150a83afc of 4 bytes by task 3371 on cpu 1:
wg_index_hashtable_insert+0xe3/0x2b0 drivers/net/wireguard/peerlookup.c:132
wg_noise_handshake_create_response+0x52c/0x5e0 drivers/net/wireguard/noise.c:713
wg_packet_send_handshake_response+0x6d/0x120 drivers/net/wireguard/send.c:94
wg_receive_handshake_packet drivers/net/wireguard/receive.c:154 [inline]
wg_packet_handshake_receive_worker+0x3cc/0x5d0 drivers/net/wireguard/receive.c:213
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
worker_thread+0x582/0x770 kernel/workqueue.c:3421
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff888150a83afc of 4 bytes by task 3656 on cpu 0:
wg_index_hashtable_lookup+0x6b/0x130 drivers/net/wireguard/peerlookup.c:211
wg_noise_handshake_consume_response+0x12a/0x800 drivers/net/wireguard/noise.c:747
wg_receive_handshake_packet drivers/net/wireguard/receive.c:166 [inline]
wg_packet_handshake_receive_worker+0x3da/0x5d0 drivers/net/wireguard/receive.c:213
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
worker_thread+0x582/0x770 kernel/workqueue.c:3421
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x86e8218e -> 0xba92c323

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3656 Comm: kworker/0:8 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: wg-kex-wg1 wg_packet_handshake_receive_worker
==================================================================


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