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From: Inki Dae <inki.dae@samsung.com>
To: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Cc: linux-samsung-soc@vger.kernel.org, sw0312.kim@samsung.com,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	kyungmin.park@samsung.com, kgene@kernel.org
Subject: Re: [PATCH] drm/exynos: Check for NULL dereference of crtc
Date: Fri, 06 Mar 2015 22:13:42 +0900	[thread overview]
Message-ID: <54F9A806.6020605@samsung.com> (raw)
In-Reply-To: <1424193281-30401-1-git-send-email-ckeepax@opensource.wolfsonmicro.com>

On 2015년 02월 18일 02:14, Charles Keepax wrote:
> The commit "drm/exynos: remove exynos_plane_dpms" (d9ea6256) removed the
> use of the enabled flag, which means that the code may attempt to call
> win_enable on a NULL crtc. This results in the following oops on

Hmm... it's strange. plane->funcs->destroy() is called prior to
crtc->funcs->destroy() so it should be exynos_crtc is not NULL. However,
it seems there is any corner case we didn't catch up.

Applied.

Thanks,
Inki Dae

> Arndale:
> 
> [    1.673479] Unable to handle kernel NULL pointer dereference at virtual address 00000368
> [    1.681500] pgd = c0004000
> [    1.684154] [00000368] *pgd=00000000
> [    1.687713] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> [    1.693012] Modules linked in:
> [    1.696045] CPU: 1 PID: 1 Comm: swapper/0 Not tainted
> 3.19.0-07545-g57485fa #1907
> [    1.703524] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> (....)
> [    2.014803] [<c02f9cfc>] (exynos_plane_destroy) from [<c02e61b4>] (drm_mode_config_cleanup+0x168/0x20c)
> [    2.024178] [<c02e61b4>] (drm_mode_config_cleanup) from [<c02f66fc>] (exynos_drm_load+0xac/0x12c)
> 
> This patch adds in a check to ensure exynos_crtc is not NULL before it
> is dereferenced.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_plane.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
> index 2dfb847..78fc0a1 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
> @@ -176,7 +176,7 @@ static int exynos_disable_plane(struct drm_plane *plane)
>  	struct exynos_drm_plane *exynos_plane = to_exynos_plane(plane);
>  	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(plane->crtc);
>  
> -	if (exynos_crtc->ops->win_disable)
> +	if (exynos_crtc && exynos_crtc->ops->win_disable)
>  		exynos_crtc->ops->win_disable(exynos_crtc,
>  					      exynos_plane->zpos);
>  
> 

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dri-devel@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Inki Dae <inki.dae@samsung.com>
To: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Cc: jy0922.shim@samsung.com, sw0312.kim@samsung.com,
	kyungmin.park@samsung.com, airlied@linux.ie, kgene@kernel.org,
	dri-devel@lists.freedesktop.org,
	linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/exynos: Check for NULL dereference of crtc
Date: Fri, 06 Mar 2015 22:13:42 +0900	[thread overview]
Message-ID: <54F9A806.6020605@samsung.com> (raw)
In-Reply-To: <1424193281-30401-1-git-send-email-ckeepax@opensource.wolfsonmicro.com>

On 2015년 02월 18일 02:14, Charles Keepax wrote:
> The commit "drm/exynos: remove exynos_plane_dpms" (d9ea6256) removed the
> use of the enabled flag, which means that the code may attempt to call
> win_enable on a NULL crtc. This results in the following oops on

Hmm... it's strange. plane->funcs->destroy() is called prior to
crtc->funcs->destroy() so it should be exynos_crtc is not NULL. However,
it seems there is any corner case we didn't catch up.

Applied.

Thanks,
Inki Dae

> Arndale:
> 
> [    1.673479] Unable to handle kernel NULL pointer dereference at virtual address 00000368
> [    1.681500] pgd = c0004000
> [    1.684154] [00000368] *pgd=00000000
> [    1.687713] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> [    1.693012] Modules linked in:
> [    1.696045] CPU: 1 PID: 1 Comm: swapper/0 Not tainted
> 3.19.0-07545-g57485fa #1907
> [    1.703524] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
> (....)
> [    2.014803] [<c02f9cfc>] (exynos_plane_destroy) from [<c02e61b4>] (drm_mode_config_cleanup+0x168/0x20c)
> [    2.024178] [<c02e61b4>] (drm_mode_config_cleanup) from [<c02f66fc>] (exynos_drm_load+0xac/0x12c)
> 
> This patch adds in a check to ensure exynos_crtc is not NULL before it
> is dereferenced.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_plane.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
> index 2dfb847..78fc0a1 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
> @@ -176,7 +176,7 @@ static int exynos_disable_plane(struct drm_plane *plane)
>  	struct exynos_drm_plane *exynos_plane = to_exynos_plane(plane);
>  	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(plane->crtc);
>  
> -	if (exynos_crtc->ops->win_disable)
> +	if (exynos_crtc && exynos_crtc->ops->win_disable)
>  		exynos_crtc->ops->win_disable(exynos_crtc,
>  					      exynos_plane->zpos);
>  
> 


  reply	other threads:[~2015-03-06 13:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-17 17:14 [PATCH] drm/exynos: Check for NULL dereference of crtc Charles Keepax
2015-03-06 13:13 ` Inki Dae [this message]
2015-03-06 13:13   ` Inki Dae
2015-03-06 14:04   ` Charles Keepax
2015-03-07 12:19     ` Inki Dae
2015-03-07 12:19       ` Inki Dae

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