linux-kernel - Re: [PATCH] drm/arm/mali: potential dereference of null pointer

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Date:   Tue, 14 Dec 2021 10:59:10 +0000
From:   Brian Starkey <brian.starkey@....com>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     liviu.dudau@....com, airlied@...ux.ie, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        nd@....com
Subject: Re: [PATCH] drm/arm/mali: potential dereference of null pointer

Hi Jiasheng,

Thanks for the patch, that's a careless copy-paste on my part :-(

On Tue, Dec 14, 2021 at 06:00:00PM +0800, Jiasheng Jiang wrote:
> The return value of kzalloc() needs to be checked.
> To avoid use of null pointer '&mw_state->base' in case of the
> failure of alloc.
> 
> Fixes: 8cbc5caf36ef ("drm: mali-dp: Add writeback connector")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---

Reviewed-by: Brian Starkey <brian.starkey@....com>

>  drivers/gpu/drm/arm/malidp_mw.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
> index f5847a79dd7e..612d386ee7d2 100644
> --- a/drivers/gpu/drm/arm/malidp_mw.c
> +++ b/drivers/gpu/drm/arm/malidp_mw.c
> @@ -70,7 +70,11 @@ static void malidp_mw_connector_reset(struct drm_connector *connector)
>  		__drm_atomic_helper_connector_destroy_state(connector->state);
>  
>  	kfree(connector->state);
> -	__drm_atomic_helper_connector_reset(connector, &mw_state->base);
> +
> +	if (mw_state)
> +		__drm_atomic_helper_connector_reset(connector, &mw_state->base);
> +	else
> +		__drm_atomic_helper_connector_reset(connector, NULL);
>  }
>  
>  static enum drm_connector_status
> -- 
> 2.25.1
>