[TCP]: In tcp_check_req, handle ACKless packets properly.

769c754e · David S. Miller · Sridhar Samudrala · 459de5c6 · 769c754e
Commit 769c754e authored Jan 30, 2003 by David S. Miller Committed by Sridhar Samudrala Jan 30, 2003
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net/ipv4/tcp_minisocks.c net/ipv4/tcp_minisocks.c +6 -0

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--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -952,6 +952,12 @@ struct sock *tcp_check_req(struct sock *sk,struct sk_buff *skb,
 	if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN))
 		goto embryonic_reset;
+	/* ACK sequence verified above, just make sure ACK is
+	 * set.  If ACK not set, just silently drop the packet.
+	 */
+	if (!(flg & TCP_FLAG_ACK))
+		return NULL;
 	/* If TCP_DEFER_ACCEPT is set, drop bare ACK. */
 	if (tp->defer_accept && TCP_SKB_CB(skb)->end_seq == req->rcv_isn+1) {
 		req->acked = 1;