Re: [PATCH mlx5-next v1] net/mlx5: Check device memory pointer before usage

[Simon Horman <horms@kernel.org>]

On Tue, Jul 01, 2025 at 03:08:12PM +0300, Leon Romanovsky wrote:
> From: Stav Aviram <saviram@nvidia.com>
> 
> Add a NULL check before accessing device memory to prevent a crash if
> dev->dm allocation in mlx5_init_once() fails.
> 
> Fixes: c9b9dcb430b3 ("net/mlx5: Move device memory management to mlx5_core")
> Signed-off-by: Stav Aviram <saviram@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> Changelog:
> v1:
>  * Removed extra IS_ERR(dm) check.
> v0:
> https://lore.kernel.org/all/e389fa6ef075af1049cd7026b912d736ebe3ad23.1751279408.git.leonro@nvidia.com
> ---
>  drivers/infiniband/hw/mlx5/dm.c                  | 2 +-
>  drivers/net/ethernet/mellanox/mlx5/core/lib/dm.c | 4 ++--
>  drivers/net/ethernet/mellanox/mlx5/core/main.c   | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/mlx5/dm.c b/drivers/infiniband/hw/mlx5/dm.c
> index b4c97fb62abf..9ded2b7c1e31 100644
> --- a/drivers/infiniband/hw/mlx5/dm.c
> +++ b/drivers/infiniband/hw/mlx5/dm.c
> @@ -282,7 +282,7 @@ static struct ib_dm *handle_alloc_dm_memic(struct ib_ucontext *ctx,
>  	int err;
>  	u64 address;
>  
> -	if (!MLX5_CAP_DEV_MEM(dm_db->dev, memic))
> +	if (!dm_db || !MLX5_CAP_DEV_MEM(dm_db->dev, memic))
>  		return ERR_PTR(-EOPNOTSUPP);

nit: -EOPNOTSUPP doesn't feel like the right error code
     in the !dm_db case.

>  
>  	dm = kzalloc(sizeof(*dm), GFP_KERNEL);

...