[PATCH 3.12 29/83] ping: prevent NULL pointer dereference on write to msg_name

Greg Kroah-Hartman
2013-12-06T22:38:39Z

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ Upstream commit cf970c002d270c36202bd5b9c2804d3097a52da0 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/ping.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)

--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -867,11 +867,13 @@ int ping_recvmsg(struct kiocb *iocb, str
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);
@@ -883,16 +885,18 @@ int ping_recvmsg(struct kiocb *iocb, str
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);