Commit e7cd17a2 authored Aug 09, 2016 by Max Kellermann Committed by Mauro Carvalho Chehab Nov 18, 2016

[media] drivers/media/media-device: fix double free bug in _unregister()



While removing all interfaces in media_device_unregister(), all
media_interface pointers are freed.  This is illegal and results in
double kfree() if any media_interface is still linked at this point;
maybe because a userspace process still has a file handle.  Once the
process closes the file handle, dvb_media_device_free() gets called,
which frees the dvb_device.intf_devnode again.

This patch removes the unnecessary kfree() call, and documents who's
responsible for really freeing it.

Signed-off-by: Max Kellermann <max.kellermann@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

parent 6753743e

drivers/media/media-device.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -801,9 +801,13 @@ void media_device_unregister(struct media_device *mdev)
		/* Remove all interfaces from the media device */
		list_for_each_entry_safe(intf, tmp_intf, &mdev->interfaces,
		graph_obj.list) {
		/*
		* Unlink the interface, but don't free it here; the
		* module which created it is responsible for freeing
		* it
		*/
		__media_remove_intf_links(intf);
		media_gobj_destroy(&intf->graph_obj);
		kfree(intf);
		}

		mutex_unlock(&mdev->graph_mutex);