6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit de5724ca38fd5e442bae9c1fab31942b6544012d upstream.
syzbot complains about a race in xfrm_lookup_with_ifid() [1]
When preparing commit 0a9e5794b21e ("xfrm: annotate data-race
around use_time") I thought xfrm_lookup_with_ifid() was modifying
a still private structure.
[1]
BUG: KCSAN: data-race in xfrm_lookup_with_ifid / xfrm_lookup_with_ifid
write to 0xffff88813ea41108 of 8 bytes by task 8150 on cpu 1:
xfrm_lookup_with_ifid+0xce7/0x12d0 net/xfrm/xfrm_policy.c:3218
xfrm_lookup net/xfrm/xfrm_policy.c:3270 [inline]
xfrm_lookup_route+0x3b/0x100 net/xfrm/xfrm_policy.c:3281
ip6_dst_lookup_flow+0x98/0xc0 net/ipv6/ip6_output.c:1246
send6+0x241/0x3c0 drivers/net/wireguard/socket.c:139
wg_socket_send_skb_to_peer+0xbd/0x130 drivers/net/wireguard/socket.c:178
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 kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
write to 0xffff88813ea41108 of 8 bytes by task 15867 on cpu 0:
xfrm_lookup_with_ifid+0xce7/0x12d0 net/xfrm/xfrm_policy.c:3218
xfrm_lookup net/xfrm/xfrm_policy.c:3270 [inline]
xfrm_lookup_route+0x3b/0x100 net/xfrm/xfrm_policy.c:3281
ip6_dst_lookup_flow+0x98/0xc0 net/ipv6/ip6_output.c:1246
send6+0x241/0x3c0 drivers/net/wireguard/socket.c:139
wg_socket_send_skb_to_peer+0xbd/0x130 drivers/net/wireguard/socket.c:178
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 kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
value changed: 0x00000000651cd9d1 -> 0x00000000651cd9d2
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15867 Comm: kworker/u4:58 Not tainted 6.6.0-rc4-syzkaller-00016-g5e62ed3b1c8a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker
Fixes: 0a9e5794b21e ("xfrm: annotate data-race around use_time")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/xfrm/xfrm_policy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3138,7 +3138,7 @@ no_transform:
}
for (i = 0; i < num_pols; i++)
- pols[i]->curlft.use_time = ktime_get_real_seconds();
+ WRITE_ONCE(pols[i]->curlft.use_time, ktime_get_real_seconds());
if (num_xfrms < 0) {
/* Prohibit the flow */
