linux-kernel - Re: [PATCH] ALSA: hda/cs_dsp_ctl: Use private

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Date: Wed, 08 May 2024 14:33:53 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Richard Fitzgerald <rf@...nsource.cirrus.com>
Cc: <tiwai@...e.com>,
	<linux-kernel@...r.kernel.org>,
	<patches@...nsource.cirrus.com>,
	<alsa-devel@...a-project.org>,
	<linux-sound@...r.kernel.org>
Subject: Re: [PATCH] ALSA: hda/cs_dsp_ctl: Use private_free for control cleanup

On Wed, 08 May 2024 11:56:27 +0200,
Richard Fitzgerald wrote:
> 
> Use the control private_free callback to free the associated data
> block. This ensures that the memory won't leak, whatever way the
> control gets destroyed.
> 
> The original implementation didn't actually remove the ALSA
> controls in hda_cs_dsp_control_remove(). It only freed the internal
> tracking structure. This meant it was possible to remove/unload the
> amp driver while leaving its ALSA controls still present in the
> soundcard. Obviously attempting to access them could cause segfaults
> or at least dereferencing stale pointers.
> 
> Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
> Fixes: 3233b978af23 ("ALSA: hda: hda_cs_dsp_ctl: Add Library to support CS_DSP ALSA controls")
> ---
> This replaces my earlier "keep it simple" attempt at cleanup.
> I decided that implementing private_free is the only sensible
> way to fix the cleanup.

Applied now.  Thanks.


Takashi