linux-cve-announce - CVE-2021-47650: ASoC: soc-compress: prevent the potentially use of null pointer

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Message-ID: <2025022649-CVE-2021-47650-d468@gregkh>
Date: Wed, 26 Feb 2025 02:54:01 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2021-47650: ASoC: soc-compress: prevent the potentially use of null pointer

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ASoC: soc-compress: prevent the potentially use of null pointer

There is one call trace that snd_soc_register_card()
->snd_soc_bind_card()->soc_init_pcm_runtime()
->snd_soc_dai_compress_new()->snd_soc_new_compress().
In the trace the 'codec_dai' transfers from card->dai_link,
and we can see from the snd_soc_add_pcm_runtime() in
snd_soc_bind_card() that, if value of card->dai_link->num_codecs
is 0, then 'codec_dai' could be null pointer caused
by index out of bound in 'asoc_rtd_to_codec(rtd, 0)'.
And snd_soc_register_card() is called by various platforms.
Therefore, it is better to add the check in the case of misusing.
And because 'cpu_dai' has already checked in soc_init_pcm_runtime(),
there is no need to check again.
Adding the check as follow, then if 'codec_dai' is null,
snd_soc_new_compress() will not pass through the check
'if (playback + capture != 1)', avoiding the leftover use of
'codec_dai'.

The Linux kernel CVE team has assigned CVE-2021-47650 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.4.189 with commit 68a69ad8df959e5211ed4a8e120783b2d352ea74
	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.10.110 with commit 4639c1d97f385f4784f44d66a3da0672f4951ada
	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.15.33 with commit fc237b8d624f4bcb0f21a532627ce4e3b3a85569
	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.16.19 with commit 08af6da684b44097ea09f1d74d5858b837ed203b
	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.17.2 with commit f69a75cb8a98c6c487d620442c68595726a69f60
	Issue introduced in 5.4 with commit 467fece8fbc6774a3a3bd0981e1a342fb5022706 and fixed in 5.18 with commit de2c6f98817fa5decb9b7d3b3a8a3ab864c10588

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47650
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	sound/soc/soc-compress.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/68a69ad8df959e5211ed4a8e120783b2d352ea74
	https://git.kernel.org/stable/c/4639c1d97f385f4784f44d66a3da0672f4951ada
	https://git.kernel.org/stable/c/fc237b8d624f4bcb0f21a532627ce4e3b3a85569
	https://git.kernel.org/stable/c/08af6da684b44097ea09f1d74d5858b837ed203b
	https://git.kernel.org/stable/c/f69a75cb8a98c6c487d620442c68595726a69f60
	https://git.kernel.org/stable/c/de2c6f98817fa5decb9b7d3b3a8a3ab864c10588