RDMA/iwpm: fix memory leak on map_info

In the cases where iwpm_hash_bucket is NULL and where function
get_mapinfo_hash_bucket returns NULL then the map_info is never added
to hash_bucket_head and hence there is a leak of map_info. Fix this
by nullifying hash_bucket_head and if that is null we know that
that map_info was not added to hash_bucket_head and hence map_info
should be free'd.

Detected by CoverityScan, CID#1222481 ("Resource Leak")

Fixes: 30dc5e63d6a5 ("RDMA/core: Add support for iWARP Port Mapper user space service")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/iwpm_util.c

@@ -114,7 +114,7 @@ int iwpm_create_mapinfo(struct sockaddr_storage *local_sockaddr,
 			struct sockaddr_storage *mapped_sockaddr,
 			u8 nl_client)
 {
-	struct hlist_head *hash_bucket_head;
+	struct hlist_head *hash_bucket_head = NULL;
 	struct iwpm_mapping_info *map_info;
 	unsigned long flags;
 	int ret = -EINVAL;
@@ -142,6 +142,9 @@ int iwpm_create_mapinfo(struct sockaddr_storage *local_sockaddr,
 		}
 	}
 	spin_unlock_irqrestore(&iwpm_mapinfo_lock, flags);
+
+	if (!hash_bucket_head)
+		kfree(map_info);
 	return ret;
 }