netdev - [PATCH net-next] net/mlx5e: Fix a use after free on error in mlx5_tc_ct_shared_counter

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Date:   Mon, 28 Sep 2020 12:05:56 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Saeed Mahameed <saeedm@...dia.com>
Cc:     Leon Romanovsky <leon@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Roi Dayan <roid@...lanox.com>, Oz Shlomo <ozsh@...lanox.com>,
        Paul Blakey <paulb@...lanox.com>,
        Eli Britstein <elibr@...lanox.com>,
        Ariel Levkovich <lariel@...dia.com>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH net-next] net/mlx5e: Fix a use after free on error in
 mlx5_tc_ct_shared_counter_get()

This code frees "shared_counter" and then dereferences on the next line
to get the error code.

Fixes: 1edae2335adf ("net/mlx5e: CT: Use the same counter for both directions")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
index b5f8ed30047b..cea2070af9af 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.c
@@ -739,6 +739,7 @@ mlx5_tc_ct_shared_counter_get(struct mlx5_tc_ct_priv *ct_priv,
 	struct mlx5_core_dev *dev = ct_priv->dev;
 	struct mlx5_ct_entry *rev_entry;
 	__be16 tmp_port;
+	int ret;
 
 	/* get the reversed tuple */
 	tmp_port = rev_tuple.port.src;
@@ -778,8 +779,9 @@ mlx5_tc_ct_shared_counter_get(struct mlx5_tc_ct_priv *ct_priv,
 	shared_counter->counter = mlx5_fc_create(dev, true);
 	if (IS_ERR(shared_counter->counter)) {
 		ct_dbg("Failed to create counter for ct entry");
+		ret = PTR_ERR(shared_counter->counter);
 		kfree(shared_counter);
-		return ERR_PTR(PTR_ERR(shared_counter->counter));
+		return ERR_PTR(ret);
 	}
 
 	refcount_set(&shared_counter->refcount, 1);
-- 
2.28.0