tipc: safely copy UDP netlink data from user

The netlink policy for TIPC_NLA_UDP_LOCAL and TIPC_NLA_UDP_REMOTE
is of type binary with a defined length. This causes the policy
framework to threat the defined length as maximum length.

There is however no protection against a user sending a smaller
amount of data. Prior to this patch this wasn't handled which could
result in a partially incomplete sockaddr_storage struct containing
uninitialized data.

In this patch we use nla_memcpy() when copying the user data. This
ensures a potential gap at the end is cleared out properly.

This was found by Julia with Coccinelle tool.

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 11 deletions

diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index f22a5bb169c9..6fe8740a226f 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -276,7 +276,7 @@ static int parse_options(struct nlattr *attrs[], struct udp_bearer *ub,
                          struct udp_media_addr *remote)
 {
         struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
-        struct sockaddr_storage *sa_local, *sa_remote;
+        struct sockaddr_storage sa_local, sa_remote;
 
         if (!attrs[TIPC_NLA_BEARER_UDP_OPTS])
                 goto err;
@@ -285,41 +285,43 @@ static int parse_options(struct nlattr *attrs[], struct udp_bearer *ub,
                              tipc_nl_udp_policy))
                 goto err;
         if (opts[TIPC_NLA_UDP_LOCAL] && opts[TIPC_NLA_UDP_REMOTE]) {
-                sa_local = nla_data(opts[TIPC_NLA_UDP_LOCAL]);
-                sa_remote = nla_data(opts[TIPC_NLA_UDP_REMOTE]);
+                nla_memcpy(&sa_local, opts[TIPC_NLA_UDP_LOCAL],
+                           sizeof(sa_local));
+                nla_memcpy(&sa_remote, opts[TIPC_NLA_UDP_REMOTE],
+                           sizeof(sa_remote));
         } else {
 err:
                 pr_err("Invalid UDP bearer configuration");
                 return -EINVAL;
         }
-        if ((sa_local->ss_family & sa_remote->ss_family) == AF_INET) {
+        if ((sa_local.ss_family & sa_remote.ss_family) == AF_INET) {
                 struct sockaddr_in *ip4;
 
-                ip4 = (struct sockaddr_in *)sa_local;
+                ip4 = (struct sockaddr_in *)&sa_local;
                 local->proto = htons(ETH_P_IP);
                 local->udp_port = ip4->sin_port;
                 local->ipv4.s_addr = ip4->sin_addr.s_addr;
 
-                ip4 = (struct sockaddr_in *)sa_remote;
+                ip4 = (struct sockaddr_in *)&sa_remote;
                 remote->proto = htons(ETH_P_IP);
                 remote->udp_port = ip4->sin_port;
                 remote->ipv4.s_addr = ip4->sin_addr.s_addr;
                 return 0;
 
 #if IS_ENABLED(CONFIG_IPV6)
-        } else if ((sa_local->ss_family & sa_remote->ss_family) == AF_INET6) {
+        } else if ((sa_local.ss_family & sa_remote.ss_family) == AF_INET6) {
                 struct sockaddr_in6 *ip6;
 
-                ip6 = (struct sockaddr_in6 *)sa_local;
+                ip6 = (struct sockaddr_in6 *)&sa_local;
                 local->proto = htons(ETH_P_IPV6);
                 local->udp_port = ip6->sin6_port;
-                local->ipv6 = ip6->sin6_addr;
+                memcpy(&local->ipv6, &ip6->sin6_addr, sizeof(struct in6_addr));
                 ub->ifindex = ip6->sin6_scope_id;
 
-                ip6 = (struct sockaddr_in6 *)sa_remote;
+                ip6 = (struct sockaddr_in6 *)&sa_remote;
                 remote->proto = htons(ETH_P_IPV6);
                 remote->udp_port = ip6->sin6_port;
-                remote->ipv6 = ip6->sin6_addr;
+                memcpy(&remote->ipv6, &ip6->sin6_addr, sizeof(struct in6_addr));
                 return 0;
 #endif
         }