[moderation] [wireguard?] KCSAN: data-race in wg_index_hashtable_insert / wg_index_hashtable_lookup (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 67f0943b394d Merge tag 'selinux-pr-20261005' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11f15835580000
kernel config: https://syzkaller.appspot.com/x/.config?x=de3702ecab64292d
dashboard link: https://syzkaller.appspot.com/bug?extid=54fe9e7dbf4babbaeea3
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [Ja...@zx2c4.com andrew...@lunn.ch da...@davemloft.net edum...@kernel.org 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/91ee5f8ac9d1/disk-67f0943b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9b3256c58885/vmlinux-67f0943b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8058dcf97617/bzImage-67f0943b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+54fe9e...@syzkaller.appspotmail.com

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

write to 0xffff88811a74a13c of 4 bytes by task 29632 on cpu 0:
wg_index_hashtable_insert+0xdb/0x2a0 drivers/net/wireguard/peerlookup.c:132
wg_noise_handshake_create_response+0x652/0x700 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+0x37d/0x570 drivers/net/wireguard/receive.c:213
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
worker_thread+0x569/0x750 kernel/workqueue.c:3560
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 to 0xffff88811a74a13c of 4 bytes by task 30503 on cpu 1:
wg_index_hashtable_lookup+0x5c/0x120 drivers/net/wireguard/peerlookup.c:211
wg_noise_handshake_consume_response+0x128/0x8f0 drivers/net/wireguard/noise.c:747
wg_receive_handshake_packet drivers/net/wireguard/receive.c:166 [inline]
wg_packet_handshake_receive_worker+0x38b/0x570 drivers/net/wireguard/receive.c:213
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
worker_thread+0x569/0x750 kernel/workqueue.c:3560
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: 0xbc95250b -> 0xcf7df5ff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 30503 Comm: kworker/1:6 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: wg-kex-wg1 wg_packet_handshake_receive_worker
==================================================================


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