Subject: [PATCH] tcp: fix validation of D-SACK

From: "Yan, Zheng" <[email-masked]>
Date: Mon, 19 Sep 2011 10:05:31 +0800

D-SACK is allowed to reside below snd_una. But the corresponding check
in tcp_is_sackblock_valid() is the exact opposite. It looks like a typo.

Signed-off-by: Zheng Yan <[email-masked]>
Acked-by: Eric Dumazet <[email-masked]>
---
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ea0d218..21fab3e 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1124,7 +1124,7 @@ static int tcp_is_sackblock_valid(struct tcp_sock *tp, int is_dsack,
 		return 0;
 
 	/* ...Then it's D-SACK, and must reside below snd_una completely */
-	if (!after(end_seq, tp->snd_una))
+	if (after(end_seq, tp->snd_una))
 		return 0;
 
 	if (!before(start_seq, tp->undo_marker))