Re: [PATCH net 1/2] net/mlx5e: fix memory leak in mlx5e_fs_tt_redirect_any_create

[Rahul Rameshbabu <rrameshbabu@nvidia.com>]

On Thu, 29 Jun, 2023 10:46:41 +0800 Zhengchao Shao <shaozhengchao@huawei.com> wrote:
> The memory pointed to by the fs->any pointer is not freed in the error
> path of mlx5e_fs_tt_redirect_any_create, which can lead to a memory leak.
> Fix by freeing the memory in the error path, thereby making the error path
> identical to mlx5e_fs_tt_redirect_any_destroy().
>
> Fixes: 0f575c20bf06 ("net/mlx5e: Introduce Flow Steering ANY API")
> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en/fs_tt_redirect.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/fs_tt_redirect.c b/drivers/net/ethernet/mellanox/mlx5/core/en/fs_tt_redirect.c
> index 03cb79adf912..9cf4ec931b8b 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/fs_tt_redirect.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/fs_tt_redirect.c
> @@ -594,7 +594,7 @@ int mlx5e_fs_tt_redirect_any_create(struct mlx5e_flow_steering *fs)
>  
>  	err = fs_any_create_table(fs);
>  	if (err)
> -		return err;
> +		goto err_free_any;
>  
>  	err = fs_any_enable(fs);
>  	if (err)
> @@ -606,7 +606,7 @@ int mlx5e_fs_tt_redirect_any_create(struct mlx5e_flow_steering *fs)
>  
>  err_destroy_table:
>  	fs_any_destroy_table(fs_any);
> -
> +err_free_any:
>  	kfree(fs_any);
>  	mlx5e_fs_set_any(fs, NULL);

We probably should update the 'any' member reference in fs to NULL
*before* free-ing fs_any. Otherwise, there is a period in time where fs
is referring to a dirty pointer value in its any member field. It's not
critical, but it makes logical sense in my opinion. Lets swap these two
lines in this patch.

>  	return err;

Thanks for the patch,

-- Rahul Rameshbabu