@@ -196,9 +196,10 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
return ERR_CAST(obj);
ret = drm_gem_handle_create(file, &obj->base, handle);
- drm_gem_object_put_unlocked(&obj->base);
- if (ret)
+ if (ret) {
+ drm_gem_object_put_unlocked(&obj->base);
return ERR_PTR(ret);
+ }
return &obj->base;
}
@@ -221,7 +222,9 @@ static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
args->size = gem_object->size;
args->pitch = pitch;
- DRM_DEBUG("Created object of size %lld\n", size);
+ drm_gem_object_put_unlocked(gem_object);
+
+ DRM_DEBUG("Created object of size %llu\n", args->size);
return 0;
}
There's two references floating around here (for the object reference, not the handle_count reference, that's a different thing): - The temporary reference held by vgem_gem_create, acquired by creating the object and released by calling drm_gem_object_put_unlocked. - The reference held by the object handle, created by drm_gem_handle_create. This one generally outlives the function, except if a 2nd thread races with a GEM_CLOSE ioctl call. So usually everything is correct, except in that race case, where the access to gem_object->size could be looking at freed data already. Which again isn't a real problem (userspace shot its feet off already with the race, we could return garbage), but maybe someone can exploit this as an information leak. Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Cc: Emil Velikov <emil.velikov@collabora.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sean Paul <seanpaul@chromium.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Eric Anholt <eric@anholt.net> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Rob Clark <robdclark@chromium.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> --- drivers/gpu/drm/vgem/vgem_drv.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)