diff mbox

drm/omap: Don't dereference list head when the connectors list is empty

Message ID 1387812473-31696-1-git-send-email-laurent.pinchart@ideasonboard.com (mailing list archive)
State New, archived
Headers show

Commit Message

Laurent Pinchart Dec. 23, 2013, 3:27 p.m. UTC
The connectors list iterator returns the list head when the list is
empty. Fix it by returning NULL in that case.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/omapdrm/omap_fb.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Rob Clark Dec. 23, 2013, 6:04 p.m. UTC | #1
On Mon, Dec 23, 2013 at 10:27 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> The connectors list iterator returns the list head when the list is
> empty. Fix it by returning NULL in that case.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thanks

Signed-off-by: Rob Clark <robdclark@gmail.com>

> ---
>  drivers/gpu/drm/omapdrm/omap_fb.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c
> index f2b8f06..1b48cf2 100644
> --- a/drivers/gpu/drm/omapdrm/omap_fb.c
> +++ b/drivers/gpu/drm/omapdrm/omap_fb.c
> @@ -301,8 +301,11 @@ struct drm_connector *omap_framebuffer_get_next_connector(
>         struct list_head *connector_list = &dev->mode_config.connector_list;
>         struct drm_connector *connector = from;
>
> -       if (!from)
> +       if (!from) {
> +               if (list_empty(connector_list))
> +                       return NULL;
>                 return list_first_entry(connector_list, typeof(*from), head);
> +       }
>
>         list_for_each_entry_from(connector, connector_list, head) {
>                 if (connector != from) {
> --
> 1.8.3.2
>
Laurent Pinchart Dec. 23, 2013, 6:15 p.m. UTC | #2
Hi Rob,

On Monday 23 December 2013 13:04:15 Rob Clark wrote:
> On Mon, Dec 23, 2013 at 10:27 AM, Laurent Pinchart
> 
> <laurent.pinchart@ideasonboard.com> wrote:
> > The connectors list iterator returns the list head when the list is
> > empty. Fix it by returning NULL in that case.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Thanks
> 
> Signed-off-by: Rob Clark <robdclark@gmail.com>

Thank you. Could you please take this in your tree, or make sure that Dave 
picks the patch from the list ?

> > ---
> > 
> >  drivers/gpu/drm/omapdrm/omap_fb.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c
> > b/drivers/gpu/drm/omapdrm/omap_fb.c index f2b8f06..1b48cf2 100644
> > --- a/drivers/gpu/drm/omapdrm/omap_fb.c
> > +++ b/drivers/gpu/drm/omapdrm/omap_fb.c
> > @@ -301,8 +301,11 @@ struct drm_connector
> > *omap_framebuffer_get_next_connector(> 
> >         struct list_head *connector_list =
> >         &dev->mode_config.connector_list;
> >         struct drm_connector *connector = from;
> > 
> > -       if (!from)
> > +       if (!from) {
> > +               if (list_empty(connector_list))
> > +                       return NULL;
> >                 return list_first_entry(connector_list, typeof(*from),
> >                 head);
> > +       }
> > 
> >         list_for_each_entry_from(connector, connector_list, head) {
> >                 if (connector != from) {
archit taneja Dec. 24, 2013, 6:35 a.m. UTC | #3
Hi,

On Monday 23 December 2013 08:57 PM, Laurent Pinchart wrote:
> The connectors list iterator returns the list head when the list is
> empty. Fix it by returning NULL in that case.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>   drivers/gpu/drm/omapdrm/omap_fb.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c
> index f2b8f06..1b48cf2 100644
> --- a/drivers/gpu/drm/omapdrm/omap_fb.c
> +++ b/drivers/gpu/drm/omapdrm/omap_fb.c
> @@ -301,8 +301,11 @@ struct drm_connector *omap_framebuffer_get_next_connector(
>   	struct list_head *connector_list = &dev->mode_config.connector_list;
>   	struct drm_connector *connector = from;
>
> -	if (!from)
> +	if (!from) {
> +		if (list_empty(connector_list))
> +			return NULL;
>   		return list_first_entry(connector_list, typeof(*from), head);

looks like there is a list function which does that too:

list_first_entry_or_null()

We could probably replace it with this.

Archit

> +	}
>
>   	list_for_each_entry_from(connector, connector_list, head) {
>   		if (connector != from) {
>
diff mbox

Patch

diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c
index f2b8f06..1b48cf2 100644
--- a/drivers/gpu/drm/omapdrm/omap_fb.c
+++ b/drivers/gpu/drm/omapdrm/omap_fb.c
@@ -301,8 +301,11 @@  struct drm_connector *omap_framebuffer_get_next_connector(
 	struct list_head *connector_list = &dev->mode_config.connector_list;
 	struct drm_connector *connector = from;
 
-	if (!from)
+	if (!from) {
+		if (list_empty(connector_list))
+			return NULL;
 		return list_first_entry(connector_list, typeof(*from), head);
+	}
 
 	list_for_each_entry_from(connector, connector_list, head) {
 		if (connector != from) {