linux-kernel - Re: [PATCH 3/3] drivers/media/media-device: fix double free bug in

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Message-ID: <20160615203753.GA30666@swift.blarg.de>
Date:	Wed, 15 Jun 2016 22:37:53 +0200
From:	Max Kellermann <max@...mpel.org>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	linux-media@...r.kernel.org, mchehab@....samsung.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] drivers/media/media-device: fix double free bug in
 _unregister()

On 2016/06/15 22:32, Shuah Khan <shuahkh@....samsung.com> wrote:
> This change introduces memory leaks, since drivers are relying on
> media_device_unregister() to free interfaces.

This is what I thought, too, until I checked the code paths.  Who adds
entries to that list?  Only media_gobj_create() does, and only when
type==MEDIA_GRAPH_INTF_DEVNODE.  That is called via
media_interface_init(), via media_devnode_create().

In the whole kernel, there are two calls to media_devnode_create():
one in dvbdev.c and another one in v4l2-dev.c.  Both callers take care
for freeing their interface.  Both would crash if somebody else would
free it for them before they get a chance to do it.  Which is the very
thing my patch addresses.

Did I miss something?

Max