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authorMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-12-15 08:01:13 -0200
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2016-01-11 12:19:14 -0200
commitcc4a82581cb604444b0f9f2e7d999624964695e2 (patch)
treebd0e2f7ef813fe7c73acef2b27d795ca0d9fa945 /drivers/media/media-entity.c
parent5c883edb5b2c34e96e57037c95f9a72c4feccc50 (diff)
download96b-common-cc4a82581cb604444b0f9f2e7d999624964695e2.tar.gz
[media] media-entity: cache media_device on object removal
As pointed by Dan, the commit f8fd4c61b5ae ("[media] media-entity: protect object creation/removal using spin lock")' leads to the following static checker warning: drivers/media/media-entity.c:781 media_remove_intf_link() error: dereferencing freed memory 'link' drivers/media/media-entity.c 777 void media_remove_intf_link(struct media_link *link) 778 { 779 spin_lock(&link->graph_obj.mdev->lock); 780 __media_remove_intf_link(link); 781 spin_unlock(&link->graph_obj.mdev->lock); In practice, I didn't see any troubles even with KASAN enabled. I guess gcc optimizer internally cached the mdev reference, instead of getting it twice. Yet, it is a very bad idea to rely on such optimization. So, let's fix the code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/media/media-entity.c')
-rw-r--r--drivers/media/media-entity.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index f88740b12879..13c8ca11f169 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -580,13 +580,15 @@ EXPORT_SYMBOL_GPL(__media_entity_remove_links);
void media_entity_remove_links(struct media_entity *entity)
{
+ struct media_device *mdev = entity->graph_obj.mdev;
+
/* Do nothing if the entity is not registered. */
- if (entity->graph_obj.mdev == NULL)
+ if (mdev == NULL)
return;
- spin_lock(&entity->graph_obj.mdev->lock);
+ spin_lock(&mdev->lock);
__media_entity_remove_links(entity);
- spin_unlock(&entity->graph_obj.mdev->lock);
+ spin_unlock(&mdev->lock);
}
EXPORT_SYMBOL_GPL(media_entity_remove_links);
@@ -781,9 +783,15 @@ EXPORT_SYMBOL_GPL(__media_remove_intf_link);
void media_remove_intf_link(struct media_link *link)
{
- spin_lock(&link->graph_obj.mdev->lock);
+ struct media_device *mdev = link->graph_obj.mdev;
+
+ /* Do nothing if the intf is not registered. */
+ if (mdev == NULL)
+ return;
+
+ spin_lock(&mdev->lock);
__media_remove_intf_link(link);
- spin_unlock(&link->graph_obj.mdev->lock);
+ spin_unlock(&mdev->lock);
}
EXPORT_SYMBOL_GPL(media_remove_intf_link);
@@ -799,12 +807,14 @@ EXPORT_SYMBOL_GPL(__media_remove_intf_links);
void media_remove_intf_links(struct media_interface *intf)
{
+ struct media_device *mdev = intf->graph_obj.mdev;
+
/* Do nothing if the intf is not registered. */
- if (intf->graph_obj.mdev == NULL)
+ if (mdev == NULL)
return;
- spin_lock(&intf->graph_obj.mdev->lock);
+ spin_lock(&mdev->lock);
__media_remove_intf_links(intf);
- spin_unlock(&intf->graph_obj.mdev->lock);
+ spin_unlock(&mdev->lock);
}
EXPORT_SYMBOL_GPL(media_remove_intf_links);