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Subject: Re: [PATCH v1] vdpa/mlx5: Fix possible failure in umem size
 calculation
To:     Eli Cohen <elic@nvidia.com>, mst@redhat.com,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
References: <20210530090349.8360-1-elic@nvidia.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <ecf0afb2-14cc-2350-894c-017ebffcdf35@redhat.com>
Date:   Mon, 31 May 2021 16:29:45 +0800
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?? 2021/5/30 ????5:03, Eli Cohen д??:
> umem size is a 32 bit unsigned value so assigning it to an int could
> cause false failures. Set the calculated value inside the function and
> modify function name to reflect the fact it updates the size.
>
> This bug was found during code review but never had real impact to this
> date.
>
> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
> Signed-off-by: Eli Cohen <elic@nvidia.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
> V0 --> V1:
>    Add more info in changelog
>
>   drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 +++++----------
>   1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 53312f0460ad..fdf3e74bffbd 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -610,8 +610,8 @@ static void cq_destroy(struct mlx5_vdpa_net *ndev, u16 idx)
>   	mlx5_db_free(ndev->mvdev.mdev, &vcq->db);
>   }
>   
> -static int umem_size(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq, int num,
> -		     struct mlx5_vdpa_umem **umemp)
> +static void set_umem_size(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq, int num,
> +			  struct mlx5_vdpa_umem **umemp)
>   {
>   	struct mlx5_core_dev *mdev = ndev->mvdev.mdev;
>   	int p_a;
> @@ -634,7 +634,7 @@ static int umem_size(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq
>   		*umemp = &mvq->umem3;
>   		break;
>   	}
> -	return p_a * mvq->num_ent + p_b;
> +	(*umemp)->size = p_a * mvq->num_ent + p_b;
>   }
>   
>   static void umem_frag_buf_free(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_umem *umem)
> @@ -650,15 +650,10 @@ static int create_umem(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *m
>   	void *in;
>   	int err;
>   	__be64 *pas;
> -	int size;
>   	struct mlx5_vdpa_umem *umem;
>   
> -	size = umem_size(ndev, mvq, num, &umem);
> -	if (size < 0)
> -		return size;
> -
> -	umem->size = size;
> -	err = umem_frag_buf_alloc(ndev, umem, size);
> +	set_umem_size(ndev, mvq, num, &umem);
> +	err = umem_frag_buf_alloc(ndev, umem, umem->size);
>   	if (err)
>   		return err;
>