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| author |   Mauro Carvalho Chehab <mchehab@osg.samsung.com> | 2015-12-15 08:01:13 -0200 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@osg.samsung.com> | 2016-01-11 12:19:14 -0200 |
| commit | cc4a82581cb604444b0f9f2e7d999624964695e2 (patch) | |
| tree | bd0e2f7ef813fe7c73acef2b27d795ca0d9fa945 /drivers/media | |
| parent | [media] media-entity: use mutes for link setup (diff) | |
| download | linux-dev-cc4a82581cb604444b0f9f2e7d999624964695e2.tar.xz linux-dev-cc4a82581cb604444b0f9f2e7d999624964695e2.zip | |
[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')
| -rw-r--r-- | drivers/media/media-entity.c | 26 |
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); |