2019-07-29 08:39:01

by Jia-Ju Bai

Subject: [PATCH] gpu: drm: radeon: Fix a possible null-pointer dereference in radeon_connector_set_property()

In radeon_connector_set_property(), there is an if statement on line 743
to check whether connector->encoder is NULL:
if (connector->encoder)

When connector->encoder is NULL, it is used on line 755:
if (connector->encoder->crtc)

Thus, a possible null-pointer dereference may occur.

To fix this bug, connector->encoder is checked before being used.

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/gpu/drm/radeon/radeon_connectors.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index c60d1a44d22a..b684cd719612 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -752,7 +752,7 @@ static int radeon_connector_set_property(struct drm_connector *connector, struct

radeon_encoder->output_csc = val;

- if (connector->encoder->crtc) {
+ if (connector->encoder && connector->encoder->crtc) {
struct drm_crtc *crtc = connector->encoder->crtc;
struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);

--
2.17.0

2019-08-01 19:01:41

by Alex Deucher

Subject: Re: [PATCH] gpu: drm: radeon: Fix a possible null-pointer dereference in radeon_connector_set_property()

On Mon, Jul 29, 2019 at 11:08 AM Jia-Ju Bai <[email protected]> wrote:
>
> In radeon_connector_set_property(), there is an if statement on line 743
> to check whether connector->encoder is NULL:
> if (connector->encoder)
>
> When connector->encoder is NULL, it is used on line 755:
> if (connector->encoder->crtc)
>
> Thus, a possible null-pointer dereference may occur.
>
> To fix this bug, connector->encoder is checked before being used.
>
> This bug is found by a static analysis tool STCheck written by us.

I believe we always have an encoder for every connector, but never
hurts to be safe. Thanks. Applied.

Alex

>
> Signed-off-by: Jia-Ju Bai <[email protected]>
> ---
> drivers/gpu/drm/radeon/radeon_connectors.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
> index c60d1a44d22a..b684cd719612 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -752,7 +752,7 @@ static int radeon_connector_set_property(struct drm_connector *connector, struct
>
> radeon_encoder->output_csc = val;
>
> - if (connector->encoder->crtc) {
> + if (connector->encoder && connector->encoder->crtc) {
> struct drm_crtc *crtc = connector->encoder->crtc;
> struct radeon_crtc *radeon_crtc = to_radeon_crtc(crtc);
>
> --
> 2.17.0
>
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