tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit.

While reading sysctl_tcp_challenge_ack_limit, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 282f23c ("tcp: implement RFC 5961 3.2") Signed-off-by: Kuniyuki Iwashima <[email protected]> Signed-off-by: David S. Miller <[email protected]>
majek · Jul 22, 2022 · db3815a · db3815a
1 parent 9fb9019
commit db3815a
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
@@ -3629,7 +3629,7 @@ static void tcp_send_challenge_ack(struct sock *sk)
 	/* Then check host-wide RFC 5961 rate limit. */
 	now = jiffies / HZ;
 	if (now != challenge_timestamp) {
-		u32 ack_limit = net->ipv4.sysctl_tcp_challenge_ack_limit;
+		u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit);
 		u32 half = (ack_limit + 1) >> 1;
 
 		challenge_timestamp = now;