[moderation] [wireguard?] KCSAN: data-race in wg_expired_retransmit_handshake / wg_packet_send_queued_handshake_initiation (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4235cb24ec1e Merge tag 'vfs-7.2-rc5.fixes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=170091b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=c64d5daea5d97a89a704
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...@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/8ee590aed190/disk-4235cb24.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/906d9483e069/vmlinux-4235cb24.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c0b70f1e3869/bzImage-4235cb24.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c64d5d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in wg_expired_retransmit_handshake / wg_packet_send_queued_handshake_initiation

read to 0xffff88811a9b0a88 of 4 bytes by interrupt on cpu 1:
wg_expired_retransmit_handshake+0x2a/0x160 drivers/net/wireguard/timers.c:46
call_timer_fn+0x3b/0x240 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x40c/0x5f0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0x31/0x70 kernel/time/timer.c:2405
handle_softirqs+0xb9/0x280 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x42/0xd0 kernel/softirq.c:735
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
sock_has_perm security/selinux/hooks.c:4925 [inline]
selinux_socket_recvmsg+0x91/0x1e0 security/selinux/hooks.c:5297
security_socket_recvmsg+0x4c/0x90 security/security.c:4330
sock_recvmsg+0x38/0x120 net/socket.c:1146
____sys_recvmsg+0xf5/0x280 net/socket.c:2904
___sys_recvmsg+0x11f/0x3a0 net/socket.c:2946
__sys_recvmsg net/socket.c:2979 [inline]
__do_sys_recvmsg net/socket.c:2985 [inline]
__se_sys_recvmsg net/socket.c:2982 [inline]
__x64_sys_recvmsg+0xd1/0x160 net/socket.c:2982
x64_sys_call+0x2b1a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:48
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88811a9b0a88 of 4 bytes by interrupt on cpu 0:
wg_packet_send_queued_handshake_initiation+0x32/0x180 drivers/net/wireguard/send.c:59
wg_expired_new_handshake+0x26/0x30 drivers/net/wireguard/timers.c:104
call_timer_fn+0x3b/0x240 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x40c/0x5f0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0x31/0x70 kernel/time/timer.c:2405
handle_softirqs+0xb9/0x280 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x42/0xd0 kernel/softirq.c:735
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x121/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000002 -> 0x00000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3635 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
==================================================================


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