2017-12-05 17:46:34

by Gustavo A. R. Silva

Subject: [PATCH] drm/fb-helper: Fix potential NULL pointer dereference

fb_helper is being dereferenced before it is null checked,
hence there is a potential null pointer dereference.

Fix this by moving the pointer dereference after fb_helper
has been null checked.

This issue was detected with the help of Coccinelle.

Fixes: c777990fb45b ("drm/fb-helper: Handle function NULL argument")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/gpu/drm/drm_fb_helper.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 6654f2f..04a3a5c 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -178,7 +178,7 @@ EXPORT_SYMBOL(drm_fb_helper_add_one_connector);
*/
int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
{
- struct drm_device *dev = fb_helper->dev;
+ struct drm_device *dev;
struct drm_connector *connector;
struct drm_connector_list_iter conn_iter;
int i, ret = 0;
@@ -186,6 +186,8 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
if (!drm_fbdev_emulation || !fb_helper)
return 0;

+ dev = fb_helper->dev;
+
mutex_lock(&fb_helper->lock);
drm_connector_list_iter_begin(dev, &conn_iter);
drm_for_each_connector_iter(connector, &conn_iter) {
--
2.7.4

2017-12-06 09:13:02

by Daniel Vetter

Subject: Re: [PATCH] drm/fb-helper: Fix potential NULL pointer dereference

On Tue, Dec 05, 2017 at 11:46:28AM -0600, Gustavo A. R. Silva wrote:
> fb_helper is being dereferenced before it is null checked,
> hence there is a potential null pointer dereference.
>
> Fix this by moving the pointer dereference after fb_helper
> has been null checked.
>
> This issue was detected with the help of Coccinelle.
>
> Fixes: c777990fb45b ("drm/fb-helper: Handle function NULL argument")
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Oops. Applied to drm-misc-next, thanks for your patch.
-Daniel

> ---
> drivers/gpu/drm/drm_fb_helper.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 6654f2f..04a3a5c 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -178,7 +178,7 @@ EXPORT_SYMBOL(drm_fb_helper_add_one_connector);
> */
> int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
> {
> - struct drm_device *dev = fb_helper->dev;
> + struct drm_device *dev;
> struct drm_connector *connector;
> struct drm_connector_list_iter conn_iter;
> int i, ret = 0;
> @@ -186,6 +186,8 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper)
> if (!drm_fbdev_emulation || !fb_helper)
> return 0;
>
> + dev = fb_helper->dev;
> +
> mutex_lock(&fb_helper->lock);
> drm_connector_list_iter_begin(dev, &conn_iter);
> drm_for_each_connector_iter(connector, &conn_iter) {
> --
> 2.7.4
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

2017-12-06 17:07:30

by Gustavo A. R. Silva

Subject: Re: [PATCH] drm/fb-helper: Fix potential NULL pointer dereference

Quoting Daniel Vetter <[email protected]>:

> On Tue, Dec 05, 2017 at 11:46:28AM -0600, Gustavo A. R. Silva wrote:
>> fb_helper is being dereferenced before it is null checked,
>> hence there is a potential null pointer dereference.
>>
>> Fix this by moving the pointer dereference after fb_helper
>> has been null checked.
>>
>> This issue was detected with the help of Coccinelle.
>>
>> Fixes: c777990fb45b ("drm/fb-helper: Handle function NULL argument")
>> Signed-off-by: Gustavo A. R. Silva <[email protected]>
>
> Oops. Applied to drm-misc-next, thanks for your patch.
> -Daniel
>

Glad to help. :)

Thanks
--
Gustavo A. R. Silva