linux-kernel - Re: [PATCH] drm/msm/mdp5: check the return of kzalloc()

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Date:   Thu, 24 Mar 2022 10:58:17 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     <xkernel.wang@...mail.com>, <robdclark@...il.com>,
        <sean@...rly.run>, <airlied@...ux.ie>, <daniel@...ll.ch>
CC:     <linux-arm-msm@...r.kernel.org>, <freedreno@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH] drm/msm/mdp5: check the return of kzalloc()



On 3/24/2022 1:36 AM, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> kzalloc() is a memory allocation function which can return NULL when
> some internal memory errors happen. So it is better to check it to
> prevent potential wrong memory access.
> 
> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
>   drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 17 ++++++++++-------
>   1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> index c6b69af..5f914cc 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c
> @@ -90,15 +90,18 @@ static void mdp5_plane_reset(struct drm_plane *plane)
>   		__drm_atomic_helper_plane_destroy_state(plane->state);
>   
>   	kfree(to_mdp5_plane_state(plane->state));
> -	mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
> +	plane->state = NULL;
>   
> -	if (plane->type == DRM_PLANE_TYPE_PRIMARY)
> -		mdp5_state->base.zpos = STAGE_BASE;
> -	else
> -		mdp5_state->base.zpos = STAGE0 + drm_plane_index(plane);
> -	mdp5_state->base.normalized_zpos = mdp5_state->base.zpos;
> +	mdp5_state = kzalloc(sizeof(*mdp5_state), GFP_KERNEL);
> +	if (mdp5_state) {
> +		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
> +			mdp5_state->base.zpos = STAGE_BASE;
> +		else
> +			mdp5_state->base.zpos = STAGE0 + drm_plane_index(plane);
> +		mdp5_state->base.normalized_zpos = mdp5_state->base.zpos;
>   
> -	__drm_atomic_helper_plane_reset(plane, &mdp5_state->base);
> +		__drm_atomic_helper_plane_reset(plane, &mdp5_state->base);
> +	}
>   }
>   
>   static struct drm_plane_state *