tcp-repair: Handle zero-length data put in rcv queue

[ 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 <xemul@parallels.com>
Reported-by: Giorgos Mavrikas <gmavrikas@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d377f4854cb853c454541062fb6f8438608d470c..c92c4da4757de5d48d0df48e711081900c5da716 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4556,6 +4556,9 @@ 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;