3.6-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Pavel Emelyanov <redacted>

[ Upstream commit c454e6111d1ef4268fe98e87087216e51c2718c3 ]

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 <redacted>
Reported-by: Giorgos Mavrikas <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/tcp_input.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c

@@ -4556,6 +4556,9 @@ int tcp_send_rcvq(struct sock *sk, struc
 	struct tcphdr *th;
 	bool fragstolen;
 
+	if (size == 0)
+		return 0;
+
 	skb = alloc_skb(size + sizeof(*th), sk->sk_allocation);
 	if (!skb)
 		goto err;