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From: "Michel Dänzer" <michel@daenzer.net>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	linux-samsung-soc@vger.kernel.org,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	dri-devel@lists.freedesktop.org,
	Mark Yao <mark.yao@rock-chips.com>
Subject: Re: [PATCH 08/13] drm/irq: Check for valid VBLANK before dereference
Date: Wed, 17 Dec 2014 12:11:11 +0900	[thread overview]
Message-ID: <5490F44F.30709@daenzer.net> (raw)
In-Reply-To: <1418748815-15434-8-git-send-email-thierry.reding@gmail.com>

On 17.12.2014 01:53, 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>
> ---
>  drivers/gpu/drm/drm_irq.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index a24658162284..cb207e047505 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -1070,10 +1070,10 @@ 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 */
> @@ -1356,6 +1356,9 @@ 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;
> 

It would probably be better to use WARN_ON_ONCE, otherwise any bugs
triggering these might flood dmesg.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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  reply	other threads:[~2014-12-17  3:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-16 16:53 [PATCH 01/13] drm/irq: Remove negative CRTC index special-case Thierry Reding
2014-12-16 16:53 ` [PATCH 02/13] drm/bochs: Store correct CRTC index in events Thierry Reding
2014-12-16 16:53 ` [PATCH 03/13] drm/exynos: " Thierry Reding
2014-12-16 16:53 ` [PATCH 04/13] drm/imx: Make pipe number unsigned Thierry Reding
2014-12-16 17:30   ` Philipp Zabel
2014-12-16 16:53 ` [PATCH 05/13] drm/imx: Store correct CRTC index in events Thierry Reding
2014-12-16 17:36   ` Philipp Zabel
2014-12-16 16:53 ` [PATCH 06/13] drm/rockchip: " Thierry Reding
2014-12-16 16:53 ` [PATCH 07/13] drm/sti: " Thierry Reding
2014-12-16 16:53 ` [PATCH 08/13] drm/irq: Check for valid VBLANK before dereference Thierry Reding
2014-12-17  3:11   ` Michel Dänzer [this message]
2014-12-16 16:53 ` [PATCH 09/13] drm/irq: Make pipe unsigned and name consistent Thierry Reding
2014-12-16 17:53   ` Daniel Vetter
2014-12-16 16:53 ` [PATCH 10/13] drm/irq: Add drm_crtc_vblank_count_and_time() Thierry Reding
2014-12-16 16:53 ` [PATCH 11/13] drm/irq: Document return values more consistently Thierry Reding
2014-12-16 18:02   ` Daniel Vetter
2014-12-16 16:53 ` [PATCH 12/13] drm/irq: Expel legacy API Thierry Reding
2014-12-16 17:59   ` Daniel Vetter
2014-12-16 18:00     ` Daniel Vetter
2014-12-16 16:53 ` [PATCH 13/13] drm/irq: Move some prototypes to drm_crtc.h Thierry Reding
  -- strict thread matches above, loose matches on Subject: below --
2015-08-12 15:00 [PATCH 01/13] drm/gma500: Sanity-check pipe index Thierry Reding
2015-08-12 15:00 ` [PATCH 08/13] drm/irq: Check for valid VBLANK before dereference Thierry Reding
2015-08-12 15:40   ` Daniel Vetter
2015-08-13  9:20     ` Thierry Reding
2015-08-13 13:05       ` Daniel Vetter

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