linux-kernel - Re: [PATCH] drm/radeon: fix a potential NULL pointer dereference

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Date:   Thu, 19 Sep 2019 19:11:42 +0200
From:   Michel Dänzer <michel@...nzer.net>
To:     Allen Pais <allen.pais@...cle.com>
Cc:     dri-devel@...ts.freedesktop.org, airlied@...ux.ie,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org
Subject: Re: [PATCH] drm/radeon: fix a potential NULL pointer dereference

On 2019-09-18 6:31 p.m., Allen Pais wrote:
> alloc_workqueue is not checked for errors and as a result,
> a potential NULL dereference could occur.
> 
> Signed-off-by: Allen Pais <allen.pais@...cle.com>
> ---
>  drivers/gpu/drm/radeon/radeon_display.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> index bd52f15..1a41764 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -683,6 +683,10 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
>  	drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
>  	radeon_crtc->crtc_id = index;
>  	radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
> +	if (unlikely(!radeon_crtc->flip_queue)) {
> +		kfree(radeon_crtc);
> +		return;
> +	}
>  	rdev->mode_info.crtcs[index] = radeon_crtc;
>  
>  	if (rdev->family >= CHIP_BONAIRE) {
> 

I'm afraid just silently leaving the CRTC uninitialized isn't a good way
to handle this. The failure would need to be propagated, probably
resulting in the driver aborting its initialization altogether.


-- 
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer