From c454e6111d1ef4268fe98e87087216e51c2718c3 Mon Sep 17 00:00:00 2001
From: Pavel Emelyanov <xemul@parallels.com>
Date: Mon, 29 Oct 2012 05:05:33 +0000
Subject: tcp-repair: Handle zero-length data put in rcv queue

When sending data into a tcp socket in repair state we should check
for the amount of data being 0 explicitly. Otherwise we'll have an skb
with seq == end_seq in rcv queue, but tcp doesn't expect this to happen
(in particular a warn_on in tcp_recvmsg shoots).

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Reported-by: Giorgos Mavrikas <gmavrikas@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1db6639..2c2b13a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4529,6 +4529,9 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
 	struct tcphdr *th;
 	bool fragstolen;
 
+	if (size == 0)
+		return 0;
+
 	skb = alloc_skb(size + sizeof(*th), sk->sk_allocation);
 	if (!skb)
 		goto err;
-- 
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