Re: [PATCH v2 12/12] ASoC: Fix use-after-free at card unregistration

From: Robert Jarzmik
Date: Mon Jun 19 2017 - 07:57:52 EST


Takashi Iwai <tiwai@xxxxxxx> writes:

> On Mon, 19 Jun 2017 09:27:09 +0200,
> Robert Jarzmik wrote:
>>
>> From: Takashi Iwai <tiwai@xxxxxxx>
>>
>> soc_cleanup_card_resources() call snd_card_free() at the last of its
>> procedure. This turned out to lead to a use-after-free.
>> PCM runtimes have been already removed via soc_remove_pcm_runtimes(),
>> while it's dereferenced later in soc_pcm_free() called via
>> snd_card_free().
>>
>> The fix is simple: just move the snd_card_free() call to the beginning
>> of the whole procedure. This also gives another benefit: it
>> guarantees that all operations have been shut down before actually
>> releasing the resources, which was racy until now.
>>
>> Reported-and-tested-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
>> Cc: <stable@xxxxxxxxxxxxxxx>
>> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
>
> This patch must be superfluous :)
Haha :)

My serie shifted by one, so the very first of the serie is therefore missing,
formerly "ALSA: ac97: split out the generic ac97 registers" in
https://patchwork.kernel.org/patch/9398143/, and the shift triggered the
inclusion of the last patch of my tree, ie. yours :)

Cheers.

--
Robert