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| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-07-24 12:12:45 +0200 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2014-08-05 11:06:52 +1000 |
| commit | 168c02ec06f891990617cee2abbba70858c071e7 (patch) | |
| tree | bbcb2fde44a5856c61594436bbe6854559073da3 /drivers/gpu/drm/drm_crtc.c | |
| parent | dff01de1c3cafb128344fe809cbca84606b1b65c (diff) | |
| download | linux-168c02ec06f891990617cee2abbba70858c071e7.tar.bz2 | |
drm: Fix race when checking for fb in the generic kms obj lookup
In my review of
commit 98f75de40e9d83c3a90d294b8fd25fa2874212a9
Author: Rob Clark <robdclark@gmail.com>
Date: Fri May 30 11:37:03 2014 -0400
drm: add object property typ
I asked for a check to make sure that we never leak an fb from the
generic mode object lookup since those have completely different
lifetime rules. Rob added it, but outside of the idr mutex, which
means that our dereference of obj->type can already chase free'd
memory.
Somehow I didn't spot this, so fix this asap.
v2: Simplify the conditionals as suggested by Chris.
Cc: Rob Clark <robdclark@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm/drm_crtc.c')
| -rw-r--r-- | drivers/gpu/drm/drm_crtc.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 3c4a62169f28..fa2be249999c 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -446,8 +446,12 @@ static struct drm_mode_object *_object_find(struct drm_device *dev, mutex_lock(&dev->mode_config.idr_mutex); obj = idr_find(&dev->mode_config.crtc_idr, id); - if (!obj || (type != DRM_MODE_OBJECT_ANY && obj->type != type) || - (obj->id != id)) + if (obj && type != DRM_MODE_OBJECT_ANY && obj->type != type) + obj = NULL; + if (obj && obj->id != id) + obj = NULL; + /* don't leak out unref'd fb's */ + if (obj && (obj->type == DRM_MODE_OBJECT_FB)) obj = NULL; mutex_unlock(&dev->mode_config.idr_mutex); @@ -474,9 +478,6 @@ struct drm_mode_object *drm_mode_object_find(struct drm_device *dev, * function.*/ WARN_ON(type == DRM_MODE_OBJECT_FB); obj = _object_find(dev, id, type); - /* don't leak out unref'd fb's */ - if (obj && (obj->type == DRM_MODE_OBJECT_FB)) - obj = NULL; return obj; } EXPORT_SYMBOL(drm_mode_object_find); |