CVE-2013-6432: Other (NVD-CWE-Other)
value: The ping_recvmsg function in net/ipv4/ping.c in the Linux kernel before 3.12.4 does not properly interact with read system calls on ping sockets, which allows local users to cause a denial of service (NULL pointer dereference and system crash) by leveraging unspecified privileges to execute a crafted application.
CWE description: NVD is only using a subset of CWE for mapping instead of the entire CWE, and the weakness type is not covered by that subset.
Published: 2013-12-09T18:55Z
Repository: https://github.com/torvalds/linux
Language: C
Files changed: net/ipv4/ping.c
Commit date: 2013-11-18 16:02:03 -0500
Commit message: 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.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Diff: diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index aacefa0caa36af..91bfe0437e7a01 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -868,15 +868,17 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	/* Copy the address and add cmsg data. */
 	if (family == AF_INET) {
 		struct sockaddr_in *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));
-		*addr_len = sizeof(*sin);
+		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));
+			*addr_len = sizeof(*sin);
+		}
 
 		if (isk->cmsg_flags)
 			ip_cmsg_recv(msg, skb);
 
 #if IS_ENABLED(CONFIG_IPV6)
@@ -884,20 +886,22 @@ 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);
 		struct sockaddr_in6 *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);
-		*addr_len = sizeof(*sin6);
+		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);
+			*addr_len = sizeof(*sin6);
+		}
 
 		if (inet6_sk(sk)->rxopt.all)
 			pingv6_ops.ip6_datagram_recv_ctl(sk, msg, skb);
 #endif
 	} else {

Vulnerable code: 		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));
		*addr_len = sizeof(*sin);
		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);
		*addr_len = sizeof(*sin6);
Fixed code: 		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));
			*addr_len = sizeof(*sin);
		}
		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);
			*addr_len = sizeof(*sin6);
		}