tipc: fix potential null pointer dereferences in some compat functions

Before calling the nla_parse_nested function, make sure the pointer to the
attribute is not null. This patch fixes several potential null pointer
dereference vulnerabilities in the tipc netlink functions.

Signed-off-by: Baozeng Ding <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/tipc/netlink_compat.c

···
 				      struct nlattr **attrs)
 {
 	struct nlattr *bearer[TIPC_NLA_BEARER_MAX + 1];
+	int err;
 
-	nla_parse_nested(bearer, TIPC_NLA_BEARER_MAX, attrs[TIPC_NLA_BEARER],
-			 NULL);
+	if (!attrs[TIPC_NLA_BEARER])
+		return -EINVAL;
+
+	err = nla_parse_nested(bearer, TIPC_NLA_BEARER_MAX,
+			       attrs[TIPC_NLA_BEARER], NULL);
+	if (err)
+		return err;
 
 	return tipc_add_tlv(msg->rep, TIPC_TLV_BEARER_NAME,
 			    nla_data(bearer[TIPC_NLA_BEARER_NAME]),
···
 	struct nlattr *link[TIPC_NLA_LINK_MAX + 1];
 	struct nlattr *prop[TIPC_NLA_PROP_MAX + 1];
 	struct nlattr *stats[TIPC_NLA_STATS_MAX + 1];
+	int err;
 
-	nla_parse_nested(link, TIPC_NLA_LINK_MAX, attrs[TIPC_NLA_LINK], NULL);
+	if (!attrs[TIPC_NLA_LINK])
+		return -EINVAL;
 
-	nla_parse_nested(prop, TIPC_NLA_PROP_MAX, link[TIPC_NLA_LINK_PROP],
-			 NULL);
+	err = nla_parse_nested(link, TIPC_NLA_LINK_MAX, attrs[TIPC_NLA_LINK],
+			       NULL);
+	if (err)
+		return err;
 
-	nla_parse_nested(stats, TIPC_NLA_STATS_MAX, link[TIPC_NLA_LINK_STATS],
-			 NULL);
+	if (!link[TIPC_NLA_LINK_PROP])
+		return -EINVAL;
+
+	err = nla_parse_nested(prop, TIPC_NLA_PROP_MAX,
+			       link[TIPC_NLA_LINK_PROP], NULL);
+	if (err)
+		return err;
+
+	if (!link[TIPC_NLA_LINK_STATS])
+		return -EINVAL;
+
+	err = nla_parse_nested(stats, TIPC_NLA_STATS_MAX,
+			       link[TIPC_NLA_LINK_STATS], NULL);
+	if (err)
+		return err;
 
 	name = (char *)TLV_DATA(msg->req);
 	if (strcmp(name, nla_data(link[TIPC_NLA_LINK_NAME])) != 0)
···
 {
 	struct nlattr *link[TIPC_NLA_LINK_MAX + 1];
 	struct tipc_link_info link_info;
+	int err;
 
-	nla_parse_nested(link, TIPC_NLA_LINK_MAX, attrs[TIPC_NLA_LINK], NULL);
+	if (!attrs[TIPC_NLA_LINK])
+		return -EINVAL;
+
+	err = nla_parse_nested(link, TIPC_NLA_LINK_MAX, attrs[TIPC_NLA_LINK],
+			       NULL);
+	if (err)
+		return err;
 
 	link_info.dest = nla_get_flag(link[TIPC_NLA_LINK_DEST]);
 	link_info.up = htonl(nla_get_flag(link[TIPC_NLA_LINK_UP]));
···
 	u32 node, depth, type, lowbound, upbound;
 	static const char * const scope_str[] = {"", " zone", " cluster",
 						 " node"};
+	int err;
 
-	nla_parse_nested(nt, TIPC_NLA_NAME_TABLE_MAX,
-			 attrs[TIPC_NLA_NAME_TABLE], NULL);
+	if (!attrs[TIPC_NLA_NAME_TABLE])
+		return -EINVAL;
 
-	nla_parse_nested(publ, TIPC_NLA_PUBL_MAX, nt[TIPC_NLA_NAME_TABLE_PUBL],
-			 NULL);
+	err = nla_parse_nested(nt, TIPC_NLA_NAME_TABLE_MAX,
+			       attrs[TIPC_NLA_NAME_TABLE], NULL);
+	if (err)
+		return err;
+
+	if (!nt[TIPC_NLA_NAME_TABLE_PUBL])
+		return -EINVAL;
+
+	err = nla_parse_nested(publ, TIPC_NLA_PUBL_MAX,
+			       nt[TIPC_NLA_NAME_TABLE_PUBL], NULL);
+	if (err)
+		return err;
 
 	ntq = (struct tipc_name_table_query *)TLV_DATA(msg->req);
 
···
 {
 	u32 type, lower, upper;
 	struct nlattr *publ[TIPC_NLA_PUBL_MAX + 1];
+	int err;
 
-	nla_parse_nested(publ, TIPC_NLA_PUBL_MAX, attrs[TIPC_NLA_PUBL], NULL);
+	if (!attrs[TIPC_NLA_PUBL])
+		return -EINVAL;
+
+	err = nla_parse_nested(publ, TIPC_NLA_PUBL_MAX, attrs[TIPC_NLA_PUBL],
+			       NULL);
+	if (err)
+		return err;
 
 	type = nla_get_u32(publ[TIPC_NLA_PUBL_TYPE]);
 	lower = nla_get_u32(publ[TIPC_NLA_PUBL_LOWER]);
···
 	u32 sock_ref;
 	struct nlattr *sock[TIPC_NLA_SOCK_MAX + 1];
 
-	nla_parse_nested(sock, TIPC_NLA_SOCK_MAX, attrs[TIPC_NLA_SOCK], NULL);
+	if (!attrs[TIPC_NLA_SOCK])
+		return -EINVAL;
+
+	err = nla_parse_nested(sock, TIPC_NLA_SOCK_MAX, attrs[TIPC_NLA_SOCK],
+			       NULL);
+	if (err)
+		return err;
 
 	sock_ref = nla_get_u32(sock[TIPC_NLA_SOCK_REF]);
 	tipc_tlv_sprintf(msg->rep, "%u:", sock_ref);
···
 				     struct nlattr **attrs)
 {
 	struct nlattr *media[TIPC_NLA_MEDIA_MAX + 1];
+	int err;
 
-	nla_parse_nested(media, TIPC_NLA_MEDIA_MAX, attrs[TIPC_NLA_MEDIA],
-			 NULL);
+	if (!attrs[TIPC_NLA_MEDIA])
+		return -EINVAL;
+
+	err = nla_parse_nested(media, TIPC_NLA_MEDIA_MAX, attrs[TIPC_NLA_MEDIA],
+			       NULL);
+	if (err)
+		return err;
 
 	return tipc_add_tlv(msg->rep, TIPC_TLV_MEDIA_NAME,
 			    nla_data(media[TIPC_NLA_MEDIA_NAME]),
···
 {
 	struct tipc_node_info node_info;
 	struct nlattr *node[TIPC_NLA_NODE_MAX + 1];
+	int err;
 
-	nla_parse_nested(node, TIPC_NLA_NODE_MAX, attrs[TIPC_NLA_NODE], NULL);
+	if (!attrs[TIPC_NLA_NODE])
+		return -EINVAL;
+
+	err = nla_parse_nested(node, TIPC_NLA_NODE_MAX, attrs[TIPC_NLA_NODE],
+			       NULL);
+	if (err)
+		return err;
 
 	node_info.addr = htonl(nla_get_u32(node[TIPC_NLA_NODE_ADDR]));
 	node_info.up = htonl(nla_get_flag(node[TIPC_NLA_NODE_UP]));
···
 {
 	__be32 id;
 	struct nlattr *net[TIPC_NLA_NET_MAX + 1];
+	int err;
 
-	nla_parse_nested(net, TIPC_NLA_NET_MAX, attrs[TIPC_NLA_NET], NULL);
+	if (!attrs[TIPC_NLA_NET])
+		return -EINVAL;
+
+	err = nla_parse_nested(net, TIPC_NLA_NET_MAX, attrs[TIPC_NLA_NET],
+			       NULL);
+	if (err)
+		return err;
+
 	id = htonl(nla_get_u32(net[TIPC_NLA_NET_ID]));
 
 	return tipc_add_tlv(msg->rep, TIPC_TLV_UNSIGNED, &id, sizeof(id));