[PATCH] tipc: fix potential null pointer dereference in the nla_data function

[Baozeng Ding <sploving1@gmail.com>]

Before calling the nla_data function, make sure the argument is not null.
Fix potential null pointer dereference vulnerability for this.

Signed-off-by: Baozeng Ding <sploving1@gmail.com>
---
 net/tipc/netlink_compat.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index f795b1d..efbba26 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -356,6 +356,9 @@ static int tipc_nl_compat_bearer_dump(struct tipc_nl_compat_msg *msg,
 	if (err)
 		return err;
 
+	if (!bearer[TIPC_NLA_BEARER_NAME])
+		return -EINVAL;
+
 	return tipc_add_tlv(msg->rep, TIPC_TLV_BEARER_NAME,
 			    nla_data(bearer[TIPC_NLA_BEARER_NAME]),
 			    nla_len(bearer[TIPC_NLA_BEARER_NAME]));
@@ -492,6 +495,9 @@ static int tipc_nl_compat_link_stat_dump(struct tipc_nl_compat_msg *msg,
 	if (err)
 		return err;
 
+	if (!link[TIPC_NLA_LINK_NAME])
+		return -EINVAL;
+
 	name = (char *)TLV_DATA(msg->req);
 	if (strcmp(name, nla_data(link[TIPC_NLA_LINK_NAME])) != 0)
 		return 0;
@@ -602,6 +608,9 @@ static int tipc_nl_compat_link_dump(struct tipc_nl_compat_msg *msg,
 	if (err)
 		return err;
 
+	if (!link[TIPC_NLA_LINK_NAME])
+		return -EINVAL;
+
 	link_info.dest = nla_get_flag(link[TIPC_NLA_LINK_DEST]);
 	link_info.up = htonl(nla_get_flag(link[TIPC_NLA_LINK_UP]));
 	strcpy(link_info.str, nla_data(link[TIPC_NLA_LINK_NAME]));
@@ -981,6 +990,9 @@ static int tipc_nl_compat_media_dump(struct tipc_nl_compat_msg *msg,
 	if (err)
 		return err;
 
+	if (!media[TIPC_NLA_MEDIA_NAME])
+		return -EINVAL;
+
 	return tipc_add_tlv(msg->rep, TIPC_TLV_MEDIA_NAME,
 			    nla_data(media[TIPC_NLA_MEDIA_NAME]),
 			    nla_len(media[TIPC_NLA_MEDIA_NAME]));
-- 
1.9.1