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

From: syzbot <[email-masked]>
Date: Mon, 28 Aug 2023 07:40:02 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    4f9e7fabf864 Merge tag 'trace-v6.5-rc6' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f1991fa80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f12c32a009b80107
dashboard link: https://syzkaller.appspot.com/bug?extid=b1c5c1efac7273c587fe
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/586c18cf5685/disk-4f9e7fab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/26437f4b2bc8/vmlinux-4f9e7fab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6be368a4b854/bzImage-4f9e7fab.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

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

read-write to 0xffff88813587e3d8 of 8 bytes by task 31333 on cpu 1:
 wg_socket_send_skb_to_peer+0xe4/0x130 drivers/net/wireguard/socket.c:183
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x128/0x320 drivers/net/wireguard/send.c:276
 process_one_work+0x434/0x860 kernel/workqueue.c:2600
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2751
 kthread+0x1d7/0x210 kernel/kthread.c:389
 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read-write to 0xffff88813587e3d8 of 8 bytes by task 8119 on cpu 0:
 wg_socket_send_skb_to_peer+0xe4/0x130 drivers/net/wireguard/socket.c:183
 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
 process_one_work+0x434/0x860 kernel/workqueue.c:2600
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2751
 kthread+0x1d7/0x210 kernel/kthread.c:389
 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x000000000000b4fc -> 0x000000000000b51c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8119 Comm: kworker/u4:63 Not tainted 6.5.0-rc7-syzkaller-00104-g4f9e7fabf864 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
==================================================================

---
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