Subject: Re: [PATCH net] net/mlx5: DR, fix memory leak in mlx5dr_cmd_create_reformat_ctx

From: Simon Horman <[email-masked]>
Date: Tue, 4 Jul 2023 15:40:44 +0100

On Tue, Jul 04, 2023 at 11:33:08AM +0800, Zhengchao Shao wrote:
> when mlx5_cmd_exec failed in mlx5dr_cmd_create_reformat_ctx, the memory
> pointed by 'in' is not released, which will cause memory leak. Move memory
> release after mlx5_cmd_exec.
> 
> Fixes: 1d9186476e12 ("net/mlx5: DR, Add direct rule command utilities")
> Signed-off-by: Zhengchao Shao <[email-masked]>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
> index 7491911ebcb5..cf5820744e99 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
> @@ -563,11 +563,11 @@ int mlx5dr_cmd_create_reformat_ctx(struct mlx5_core_dev *mdev,
>  		memcpy(pdata, reformat_data, reformat_size);
>  
>  	err = mlx5_cmd_exec(mdev, in, inlen, out, sizeof(out));
> +	kvfree(in);
>  	if (err)
>  		return err;
>  
>  	*reformat_id = MLX5_GET(alloc_packet_reformat_context_out, out, packet_reformat_id);
> -	kvfree(in);
>  
>  	return err;
>  }

Hi Zhengchao Shao,

I agree this is a correct fix.
However, I think a more idiomatic approach to this problem
would be to use a goto label. Something like this (completely untested!).

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
index 7491911ebcb5..8c2a34a0d6be 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_cmd.c
@@ -564,11 +564,12 @@ int mlx5dr_cmd_create_reformat_ctx(struct mlx5_core_dev *mdev,
 
 	err = mlx5_cmd_exec(mdev, in, inlen, out, sizeof(out));
 	if (err)
-		return err;
+		goto err_free_in;
 
 	*reformat_id = MLX5_GET(alloc_packet_reformat_context_out, out, packet_reformat_id);
-	kvfree(in);
 
+err_free_in:
+	kvfree(in);
 	return err;
 }