[PATCH 1/1] radeon: fix a possible null pointer dereference

[PATCH 1/1] radeon: fix a possible null pointer dereference

[Yuanjun Gong]

From: Gong Yuanjun <ruc_gongyuanjun@163.com>

In radeon_fp_native_mode(), the return value of drm_mode_duplicate()
is assigned to mode, which will lead to a NULL pointer dereference
on failure of drm_mode_duplicate(). Add a check to avoid npd.

The failure status of drm_cvt_mode() on the other path is checked too.

Signed-off-by: Gong Yuanjun <ruc_gongyuanjun@163.com>
---
 drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 0cb1345c6ba4..fabe4f4ca124 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -473,6 +473,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
 	    native_mode->vdisplay != 0 &&
 	    native_mode->clock != 0) {
 		mode = drm_mode_duplicate(dev, native_mode);
+		if (!mode)
+			return NULL;
 		mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
 		drm_mode_set_name(mode);
 
@@ -487,6 +489,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
 		 * simpler.
 		 */
 		mode = drm_cvt_mode(dev, native_mode->hdisplay, native_mode->vdisplay, 60, true, false, false);
+		if (!mode)
+			return NULL;
 		mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
 		DRM_DEBUG_KMS("Adding cvt approximation of native panel mode %s\n", mode->name);
 	}
-- 
2.17.1

Re: [PATCH 1/1] radeon: fix a possible null pointer dereference

[Greg KH]

On Tue, May 17, 2022 at 05:57:00PM +0800, Yuanjun Gong wrote:
> From: Gong Yuanjun <ruc_gongyuanjun@163.com>
> 
> In radeon_fp_native_mode(), the return value of drm_mode_duplicate()
> is assigned to mode, which will lead to a NULL pointer dereference
> on failure of drm_mode_duplicate(). Add a check to avoid npd.
> 
> The failure status of drm_cvt_mode() on the other path is checked too.
> 
> Signed-off-by: Gong Yuanjun <ruc_gongyuanjun@163.com>
> ---
>  drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index 0cb1345c6ba4..fabe4f4ca124 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -473,6 +473,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
>  	    native_mode->vdisplay != 0 &&
>  	    native_mode->clock != 0) {
>  		mode = drm_mode_duplicate(dev, native_mode);
> +		if (!mode)
> +			return NULL;
>  		mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
>  		drm_mode_set_name(mode);
>  
> @@ -487,6 +489,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
>  		 * simpler.
>  		 */
>  		mode = drm_cvt_mode(dev, native_mode->hdisplay, native_mode->vdisplay, 60, true, false, false);
> +		if (!mode)
> +			return NULL;
>  		mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
>  		DRM_DEBUG_KMS("Adding cvt approximation of native panel mode %s\n", mode->name);
>  	}
> -- 
> 2.17.1
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

Re: [PATCH 1/1] radeon: fix a possible null pointer dereference

[Alex Deucher]

Applied.  Thanks!

On Tue, May 17, 2022 at 9:13 AM Yuanjun Gong <ruc_gongyuanjun@163.com> wrote:
>
> From: Gong Yuanjun <ruc_gongyuanjun@163.com>
>
> In radeon_fp_native_mode(), the return value of drm_mode_duplicate()
> is assigned to mode, which will lead to a NULL pointer dereference
> on failure of drm_mode_duplicate(). Add a check to avoid npd.
>
> The failure status of drm_cvt_mode() on the other path is checked too.
>
> Signed-off-by: Gong Yuanjun <ruc_gongyuanjun@163.com>
> ---
>  drivers/gpu/drm/radeon/radeon_connectors.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index 0cb1345c6ba4..fabe4f4ca124 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -473,6 +473,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
>             native_mode->vdisplay != 0 &&
>             native_mode->clock != 0) {
>                 mode = drm_mode_duplicate(dev, native_mode);
> +               if (!mode)
> +                       return NULL;
>                 mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
>                 drm_mode_set_name(mode);
>
> @@ -487,6 +489,8 @@ static struct drm_display_mode *radeon_fp_native_mode(struct drm_encoder *encode
>                  * simpler.
>                  */
>                 mode = drm_cvt_mode(dev, native_mode->hdisplay, native_mode->vdisplay, 60, true, false, false);
> +               if (!mode)
> +                       return NULL;
>                 mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
>                 DRM_DEBUG_KMS("Adding cvt approximation of native panel mode %s\n", mode->name);
>         }
> --
> 2.17.1
>