tcp: Fix a data-race around sysctl_tcp_autocorking.

While reading sysctl_tcp_autocorking, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: f54b311142a9 ("tcp: auto corking")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2faaaaf..a11e5de 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -686,7 +686,7 @@ static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
                                int size_goal)
 {
        return skb->len < size_goal &&
-              sock_net(sk)->ipv4.sysctl_tcp_autocorking &&
+              READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_autocorking) &&
               !tcp_rtx_queue_empty(sk) &&
               refcount_read(&sk->sk_wmem_alloc) > skb->truesize &&
               tcp_skb_can_collapse_to(skb);