return 0 when MSG_OOB in ping_recvmsg

[Dave Jones <davej@redhat.com>]

If a packet causes the 'if (flags & MSG_OOB)' test this function does first
thing is true, it returns an uninitialised variable from the stack.

There may be a better return code for this failure, but returning
'0 bytes copied' seems better than just returning garbage.

Signed-off-by: Dave Jones <davej@redhat.com>

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index aea5a19..0823562 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -626,7 +626,7 @@ static int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	struct inet_sock *isk = inet_sk(sk);
 	struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
 	struct sk_buff *skb;
-	int copied, err;
+	int copied, err = 0;
 
 	pr_debug("ping_recvmsg(sk=%p,sk->num=%u)\n", isk, isk->inet_num);