[PATCH][next] net/mlx5e: Fix potential null pointer dereference

From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Saeed Mahameed <saeedm@nvidia.com>,
	Leon Romanovsky <leon@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Roi Dayan <roid@mellanox.com>,
	Vlad Buslov <vladbu@nvidia.com>,
	Ariel Levkovich <lariel@mellanox.com>
Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>
Subject: [PATCH][next] net/mlx5e: Fix potential null pointer dereference
Date: Fri, 25 Sep 2020 11:49:13 -0500	[thread overview]
Message-ID: <20200925164913.GA18472@embeddedor> (raw)

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: c620b772152b ("net/mlx5: Refactor tc flow attributes structure")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index f815b0c60a6c..fb27154bfddb 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -4534,20 +4534,22 @@ 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++)
-- 
2.27.0

