Re: [PATCH V2] net/mlx5e: fix potential null dereference in mlx5e_tc_nic_create_miss_table

[Simon Horman <horms@kernel.org>]

On Mon, Apr 07, 2025 at 03:20:31PM +0800, Charles Han wrote:
> mlx5_get_flow_namespace() may return a NULL pointer, dereferencing it
> without NULL check may lead to NULL dereference.
> Add a NULL check for ns.
> 
> Fixes: 66cb64e292d2 ("net/mlx5e: TC NIC mode, fix tc chains miss table")
> Signed-off-by: Charles Han <hanchunchao@inspur.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> index 9ba99609999f..c2f23ac95c3d 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
> @@ -5216,6 +5216,10 @@ static int mlx5e_tc_nic_create_miss_table(struct mlx5e_priv *priv)
>  	ft_attr.level = MLX5E_TC_MISS_LEVEL;
>  	ft_attr.prio = 0;
>  	ns = mlx5_get_flow_namespace(priv->mdev, MLX5_FLOW_NAMESPACE_KERNEL);
> +	if (!ns) {
> +		netdev_err(priv->mdev, "Failed to get flow namespace\n");

Hi Charles,

This does not seem to be correct. gcc-14.2.0 says:

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c: In function 'mlx5e_tc_nic_create_miss_table':
drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:5220:32: error: passing argument 1 of 'netdev_err' from incompatible pointer type [-Wincompatible-pointer-types]
 5220 |                 netdev_err(priv->mdev, "Failed to get flow namespace\n");
      |                            ~~~~^~~~~~
      |                                |
      |                                struct mlx5_core_dev *
In file included from ./include/linux/skbuff.h:39,
                 from ./include/linux/netlink.h:7,
                 from ./include/net/flow_offload.h:6,
                 from drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:34:
./include/net/net_debug.h:20:42: note: expected 'const struct net_device *' but argument is of type 'struct mlx5_core_dev *'
   20 | void netdev_err(const struct net_device *dev, const char *format, ...);
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~^~~

...

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pw-bot: changes-requested