[PATCH v2] net/mlx4_en: Fix an error handling path in 'mlx4_en_init_netdev()'

[PATCH v2] net/mlx4_en: Fix an error handling path in 'mlx4_en_init_netdev()'

[Christophe JAILLET]

If an error occurs, 'mlx4_en_destroy_netdev()' is called.
It then calls 'mlx4_en_free_resources()' which does the needed resources
cleanup.

So, doing some explicit kfree in the error handling path would lead to
some double kfree.

Simplify code to avoid such a case.

Fixes: 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings scheme")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
v1 -> v2 : rewrite the fix as explained by Tariq Toukan
           (this 2nd version may have been posted twice, once without the
           v2 tag. PLease ignore the first one)
---

 drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index e0adac4a9a19..9670b33fc9b1 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -3324,12 +3324,11 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
 					   MAX_TX_RINGS, GFP_KERNEL);
 		if (!priv->tx_ring[t]) {
 			err = -ENOMEM;
-			goto err_free_tx;
+			goto out;
 		}
 		priv->tx_cq[t] = kzalloc(sizeof(struct mlx4_en_cq *) *
 					 MAX_TX_RINGS, GFP_KERNEL);
 		if (!priv->tx_cq[t]) {
-			kfree(priv->tx_ring[t]);
 			err = -ENOMEM;
 			goto out;
 		}
@@ -3582,11 +3581,6 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
 
 	return 0;
 
-err_free_tx:
-	while (t--) {
-		kfree(priv->tx_ring[t]);
-		kfree(priv->tx_cq[t]);
-	}
 out:
 	mlx4_en_destroy_netdev(dev);
 	return err;
-- 
2.17.0

Re: [PATCH v2] net/mlx4_en: Fix an error handling path in 'mlx4_en_init_netdev()'

[Tariq Toukan]

On 10/05/2018 10:06 AM, Christophe JAILLET wrote:
> If an error occurs, 'mlx4_en_destroy_netdev()' is called.
> It then calls 'mlx4_en_free_resources()' which does the needed resources
> cleanup.
> 
> So, doing some explicit kfree in the error handling path would lead to
> some double kfree.
> 
> Simplify code to avoid such a case.
> 
> Fixes: 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings scheme")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> v1 -> v2 : rewrite the fix as explained by Tariq Toukan
>             (this 2nd version may have been posted twice, once without the
>             v2 tag. PLease ignore the first one)
> ---
> 
>   drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 8 +-------
>   1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> index e0adac4a9a19..9670b33fc9b1 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> @@ -3324,12 +3324,11 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
>   					   MAX_TX_RINGS, GFP_KERNEL);
>   		if (!priv->tx_ring[t]) {
>   			err = -ENOMEM;
> -			goto err_free_tx;
> +			goto out;
>   		}
>   		priv->tx_cq[t] = kzalloc(sizeof(struct mlx4_en_cq *) *
>   					 MAX_TX_RINGS, GFP_KERNEL);
>   		if (!priv->tx_cq[t]) {
> -			kfree(priv->tx_ring[t]);
>   			err = -ENOMEM;
>   			goto out;
>   		}
> @@ -3582,11 +3581,6 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
>   
>   	return 0;
>   
> -err_free_tx:
> -	while (t--) {
> -		kfree(priv->tx_ring[t]);
> -		kfree(priv->tx_cq[t]);
> -	}
>   out:
>   	mlx4_en_destroy_netdev(dev);
>   	return err;
> 

Reviewed-by: Tariq Toukan <tariqt@mellanox.com>

Thanks Christophe.

Re: [PATCH v2] net/mlx4_en: Fix an error handling path in 'mlx4_en_init_netdev()'

[David Miller]

From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Date: Thu, 10 May 2018 09:06:04 +0200

> If an error occurs, 'mlx4_en_destroy_netdev()' is called.
> It then calls 'mlx4_en_free_resources()' which does the needed resources
> cleanup.
> 
> So, doing some explicit kfree in the error handling path would lead to
> some double kfree.
> 
> Simplify code to avoid such a case.
> 
> Fixes: 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings scheme")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Applied and queued up for -stable, thanks.