econet: disallow NULL remote addr for sendmsg(), fixes CVE-2010-3849

Later parts of econet_sendmsg() rely on saddr != NULL, so return early
with EINVAL if NULL was passed otherwise an oops may occur.

Signed-off-by: Phil Blundell <philb@gnu.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 18 deletions

diff --git a/net/econet/af_econet.c b/net/econet/af_econet.c
index f8c1ae4b41f0..e366f1bef91f 100644
--- a/net/econet/af_econet.c
+++ b/net/econet/af_econet.c
@@ -297,23 +297,14 @@ static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
 
         mutex_lock(&econet_mutex);
 
-        if (saddr == NULL) {
-                struct econet_sock *eo = ec_sk(sk);
-
-                addr.station = eo->station;
-                addr.net     = eo->net;
-                port         = eo->port;
-                cb           = eo->cb;
-        } else {
-                if (msg->msg_namelen < sizeof(struct sockaddr_ec)) {
-                        mutex_unlock(&econet_mutex);
-                        return -EINVAL;
-                }
-                addr.station = saddr->addr.station;
-                addr.net = saddr->addr.net;
-                port = saddr->port;
-                cb = saddr->cb;
-        }
+        if (saddr == NULL || msg->msg_namelen < sizeof(struct sockaddr_ec)) {
+                mutex_unlock(&econet_mutex);
+                return -EINVAL;
+        }
+        addr.station = saddr->addr.station;
+        addr.net = saddr->addr.net;
+        port = saddr->port;
+        cb = saddr->cb;
 
         /* Look for a device with the right network number. */
         dev = net2dev_map[addr.net];
@@ -351,7 +342,6 @@ static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
 
                 eb = (struct ec_cb *)&skb->cb;
 
-                /* BUG: saddr may be NULL */
                 eb->cookie = saddr->cookie;
                 eb->sec = *saddr;
                 eb->sent = ec_tx_done;