Re: [PATCH 08/13] drm/irq: Check for valid VBLANK before dereference

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Aug 12, 2015 at 05:00:30PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> When accessing the array of per-CRTC VBLANK structures we must always
> check that the index into the array is valid before dereferencing to
> avoid crashing.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>

This misses vblank_reset (I guess that function is newer than your
patches). Can you please do a follow-up? I merged this one meanwhile.

I also squashed in a whitespace fixup in vblank_count I spotted while
reviewing this one here.
-Daniel

> ---
>  drivers/gpu/drm/drm_irq.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index 5c666c780fe9..a957b9618e85 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -1110,10 +1110,10 @@ void drm_vblank_put(struct drm_device *dev, int crtc)
>  {
>  	struct drm_vblank_crtc *vblank = &dev->vblank[crtc];
>  
> -	if (WARN_ON(atomic_read(&vblank->refcount) == 0))
> +	if (WARN_ON(crtc >= dev->num_crtcs))
>  		return;
>  
> -	if (WARN_ON(crtc >= dev->num_crtcs))
> +	if (WARN_ON(atomic_read(&vblank->refcount) == 0))
>  		return;
>  
>  	/* Last user schedules interrupt disable */
> @@ -1158,6 +1158,9 @@ void drm_wait_one_vblank(struct drm_device *dev, int crtc)
>  	int ret;
>  	u32 last;
>  
> +	if (WARN_ON(crtc >= dev->num_crtcs))
> +		return;
> +
>  	ret = drm_vblank_get(dev, crtc);
>  	if (WARN(ret, "vblank not available on crtc %i, ret=%i\n", crtc, ret))
>  		return;
> @@ -1428,6 +1431,9 @@ void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
>  	if (!dev->num_crtcs)
>  		return;
>  
> +	if (WARN_ON(crtc >= dev->num_crtcs))
> +		return;
> +
>  	if (vblank->inmodeset) {
>  		spin_lock_irqsave(&dev->vbl_lock, irqflags);
>  		dev->vblank_disable_allowed = true;
> -- 
> 2.4.5
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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