From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Mon, 18 Nov 2013 06:07:45 +0000 (+0100)
Subject: ping: prevent NULL pointer dereference on write to msg_name
X-Git-Tag: firefly_0821_release~4090^2~397
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5a0312add72620b4bd67ccb7cde887ef2b95cd6d;p=firefly-linux-kernel-4.4.55.git

ping: prevent NULL pointer dereference on write to msg_name

A plain read() on a socket does set msg->msg_name to NULL. So check for
NULL pointer first.

[Backport of net-next cf970c002d270c36202bd5b9c2804d3097a52da0]

Bug: 12780426
Change-Id: I3df76aca2fa56478b9a33c404f7b1f0940475ef7
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
---

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 0f419a2208ff..edd6e74cad35 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -875,10 +875,12 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	/* Copy the address and add cmsg data. */
 	if (family == AF_INET) {
 		sin = (struct sockaddr_in *) msg->msg_name;
-		sin->sin_family = AF_INET;
-		sin->sin_port = 0 /* skb->h.uh->source */;
-		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
-		memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+		if (sin) {
+			sin->sin_family = AF_INET;
+			sin->sin_port = 0 /* skb->h.uh->source */;
+			sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
+			memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+		}
 
 		if (isk->cmsg_flags)
 			ip_cmsg_recv(msg, skb);
@@ -888,16 +890,18 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		struct ipv6_pinfo *np = inet6_sk(sk);
 		struct ipv6hdr *ip6 = ipv6_hdr(skb);
 		sin6 = (struct sockaddr_in6 *) msg->msg_name;
-		sin6->sin6_family = AF_INET6;
-		sin6->sin6_port = 0;
-		sin6->sin6_addr = ip6->saddr;
-
-		sin6->sin6_flowinfo = 0;
-		if (np->sndflow)
-			sin6->sin6_flowinfo = ip6_flowinfo(ip6);
 
-		sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
-							  IP6CB(skb)->iif);
+		if (sin6) {
+			sin6->sin6_family = AF_INET6;
+			sin6->sin6_port = 0;
+			sin6->sin6_addr = ip6->saddr;
+			sin6->sin6_flowinfo = 0;
+			if (np->sndflow)
+				sin6->sin6_flowinfo = ip6_flowinfo(ip6);
+			sin6->sin6_scope_id =
+				ipv6_iface_scope_id(&sin6->sin6_addr,
+						    IP6CB(skb)->iif);
+		}
 
 		if (inet6_sk(sk)->rxopt.all)
 			pingv6_ops.ip6_datagram_recv_ctl(sk, msg, skb);