[PATCH] net/ping: handle protocol mismatching scenario

ping_lookup() may return a wrong sock if sk_buff's and sock's protocols
dont' match. For example, sk_buff's protocol is ETH_P_IPV6, but sock's
sk_family is AF_INET, in that case, if sk->sk_bound_dev_if is zero, a wrong
sock will be returned.
the fix is to "continue" the searching, if no matching, return NULL.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <redacted>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <redacted>
Cc: Patrick McHardy <redacted>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Jane Zhou <redacted>
Signed-off-by: Yiwei Zhao <redacted>
---
 net/ipv4/ping.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index fc1c4b1..8892913 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c

@@ -214,6 +214,8 @@ static struct sock *ping_lookup(struct net *net, struct sk_buff *skb, u16 ident)
 					     &ipv6_hdr(skb)->daddr))
 				continue;
 #endif
+		} else {
+			continue;
 		}
 
 		if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)

-- 
1.8.0