tcp: Always set options to 0 before calling tcp_established_options

Andi Kleen · davem330 · commit 5843ef421311 · 2013-10-02T16:32:43.000-04:00
tcp_established_options assumes opts-&gt;options is 0 before calling,
as it read modify writes it.

For the tcp_current_mss() case the opts structure is not zeroed,
so this can be done with uninitialized values.

This is ok, because -&gt;options is not read in this path.
But it's still better to avoid the operation on the uninitialized
field. This shuts up a static code analyzer, and presumably
may help the optimizer.

Cc: netdev@vger.kernel.org
Signed-off-by: Andi Kleen &lt;ak@linux.intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
@@ -637,6 +637,8 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
 	unsigned int size = 0;
 	unsigned int eff_sacks;
 
+	opts->options = 0;
+
 #ifdef CONFIG_TCP_MD5SIG
 	*md5 = tp->af_specific->md5_lookup(sk, sk);
 	if (unlikely(*md5)) {
