net: rds: drop VLA in rds_walk_conn_path_info()

Avoid VLA[1] by using an already allocated buffer passed
by the caller.

[1] https://lkml.org/lkml/2018/3/7/621Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/connection.c

@@ -578,9 +578,9 @@ static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
 				    struct rds_info_iterator *iter,
 				    struct rds_info_lengths *lens,
 				    int (*visitor)(struct rds_conn_path *, void *),
+				    u64 *buffer,
 				    size_t item_len)
 {
-	u64  buffer[(item_len + 7) / 8];
 	struct hlist_head *head;
 	struct rds_connection *conn;
 	size_t i;
@@ -649,8 +649,11 @@ static void rds_conn_info(struct socket *sock, unsigned int len,
 			  struct rds_info_iterator *iter,
 			  struct rds_info_lengths *lens)
 {
+	u64 buffer[(sizeof(struct rds_info_connection) + 7) / 8];
+
 	rds_walk_conn_path_info(sock, len, iter, lens,
 				rds_conn_info_visitor,
+				buffer,
 				sizeof(struct rds_info_connection));
 }