net/mlx5e: Fix potential null pointer dereference

Calls to kzalloc() and kvzalloc() should be null-checked
in order to avoid any potential failures. In this case,
a potential null pointer dereference.

Fix this by adding null checks for _parse_attr_ and _flow_
right after allocation.

Addresses-Coverity-ID: 1497154 ("Dereference before null check")
Fixes: c620b77215 ("net/mlx5: Refactor tc flow attributes structure")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -4536,20 +4536,22 @@ mlx5e_alloc_flow(struct mlx5e_priv *priv, int attr_size,
 	struct mlx5e_tc_flow_parse_attr *parse_attr;
 	struct mlx5_flow_attr *attr;
 	struct mlx5e_tc_flow *flow;
-	int out_index, err;
+	int err = -ENOMEM;
+	int out_index;
 
 	flow = kzalloc(sizeof(*flow), GFP_KERNEL);
 	parse_attr = kvzalloc(sizeof(*parse_attr), GFP_KERNEL);
+	if (!parse_attr || !flow)
+		goto err_free;
 
 	flow->flags = flow_flags;
 	flow->cookie = f->cookie;
 	flow->priv = priv;
 
 	attr = mlx5_alloc_flow_attr(get_flow_name_space(flow));
-	if (!parse_attr || !flow || !attr) {
-		err = -ENOMEM;
+	if (!attr)
 		goto err_free;
-	}
+
 	flow->attr = attr;
 
 	for (out_index = 0; out_index < MLX5_MAX_FLOW_FWD_VPORTS; out_index++)