[PATCH] drm/exynos: Avoid NULL pointer dereference in resume if bind failed

[PATCH] drm/exynos: Avoid NULL pointer dereference in resume if bind failed

[Charles Keepax]

If binding failed calling exynos_dp_enable in exynos_dp_resume will
result in several NULL pointer dereferences. It is much better to
simply skip suspend/resume handling if bind has failed, do so by
checking if a drm_dev exists.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
---
 drivers/gpu/drm/exynos/exynos_dp_core.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.c b/drivers/gpu/drm/exynos/exynos_dp_core.c
index d66ade0..48baf07 100644
--- a/drivers/gpu/drm/exynos/exynos_dp_core.c
+++ b/drivers/gpu/drm/exynos/exynos_dp_core.c
@@ -1388,6 +1388,9 @@ static int exynos_dp_suspend(struct device *dev)
 {
 	struct exynos_dp_device *dp = dev_get_drvdata(dev);
 
+	if (!dp->drm_dev)
+		return 0;
+
 	exynos_dp_disable(&dp->encoder);
 	return 0;
 }
@@ -1396,6 +1399,9 @@ static int exynos_dp_resume(struct device *dev)
 {
 	struct exynos_dp_device *dp = dev_get_drvdata(dev);
 
+	if (!dp->drm_dev)
+		return 0;
+
 	exynos_dp_enable(&dp->encoder);
 	return 0;
 }
-- 
1.7.2.5

Re: [PATCH] drm/exynos: Avoid NULL pointer dereference in resume if bind failed

[Inki Dae]

Hi,

On 2015년 09월 28일 01:11, Charles Keepax wrote:
> If binding failed calling exynos_dp_enable in exynos_dp_resume will
> result in several NULL pointer dereferences. It is much better to
> simply skip suspend/resume handling if bind has failed, do so by
> checking if a drm_dev exists.

Thanks for your patch. However, the pm interfaces of KMS drivers aren't
required because these are controlled by top of Exynos drm driver and
connector dpms. So I posted a patch that it removes pm interfaces of dp
driver.

Thanks,
Inki Dae

> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
> ---
>  drivers/gpu/drm/exynos/exynos_dp_core.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.c b/drivers/gpu/drm/exynos/exynos_dp_core.c
> index d66ade0..48baf07 100644
> --- a/drivers/gpu/drm/exynos/exynos_dp_core.c
> +++ b/drivers/gpu/drm/exynos/exynos_dp_core.c
> @@ -1388,6 +1388,9 @@ static int exynos_dp_suspend(struct device *dev)
>  {
>  	struct exynos_dp_device *dp = dev_get_drvdata(dev);
>  
> +	if (!dp->drm_dev)
> +		return 0;
> +
>  	exynos_dp_disable(&dp->encoder);
>  	return 0;
>  }
> @@ -1396,6 +1399,9 @@ static int exynos_dp_resume(struct device *dev)
>  {
>  	struct exynos_dp_device *dp = dev_get_drvdata(dev);
>  
> +	if (!dp->drm_dev)
> +		return 0;
> +
>  	exynos_dp_enable(&dp->encoder);
>  	return 0;
>  }
> 

Re: [PATCH] drm/exynos: Avoid NULL pointer dereference in resume if bind failed

[Charles Keepax]

On Wed, Sep 30, 2015 at 08:26:37PM +0900, Inki Dae wrote:
> Hi,
> 
> On 2015년 09월 28일 01:11, Charles Keepax wrote:
> > If binding failed calling exynos_dp_enable in exynos_dp_resume will
> > result in several NULL pointer dereferences. It is much better to
> > simply skip suspend/resume handling if bind has failed, do so by
> > checking if a drm_dev exists.
> 
> Thanks for your patch. However, the pm interfaces of KMS drivers aren't
> required because these are controlled by top of Exynos drm driver and
> connector dpms. So I posted a patch that it removes pm interfaces of dp
> driver.

No problems at all, as long as my Arndale starts resuming without
a NULL pointer I am happy :-)

Had a quick test of your patch it appears to fix my issue as well
so totally fine with that.

Thanks,
Charles