From: Sabrina Dubroca <sdubr...@redhat.com>

JIRA: https://issues.redhat.com/browse/RHEL-31751

commit de5724ca38fd5e442bae9c1fab31942b6544012d
Author: Eric Dumazet <eduma...@google.com>
Date:   Wed Oct 11 10:24:29 2023 +0000

    xfrm: fix a data-race in xfrm_lookup_with_ifid()

    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 <syzkal...@googlegroups.com>
    Signed-off-by: Eric Dumazet <eduma...@google.com>
    Cc: Steffen Klassert <steffen.klass...@secunet.com>
    Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>

Signed-off-by: Sabrina Dubroca <sdubr...@redhat.com>

https://virtuozzo.atlassian.net/browse/VSTOR-101702
(cherry picked from CentOS Stream commit 
a8d0aa5863643d67a2a61a9e9d6135a24d248f37)
Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com>

Feature: fix ms/xfrm
---
 net/xfrm/xfrm_policy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 52d45c5a7fb0..ce785a556cef 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3221,7 +3221,7 @@ struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
        }
 
        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 */
-- 
2.43.0

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