Subject: CVE-2024-46793: ASoC: Intel: Boards: Fix NULL pointer deref in BYT/CHT boards harder

From: Greg Kroah-Hartman <[email-masked]>

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

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

ASoC: Intel: Boards: Fix NULL pointer deref in BYT/CHT boards harder

Since commit 13f58267cda3 ("ASoC: soc.h: don't create dummy Component
via COMP_DUMMY()") dummy codecs declared like this:

SND_SOC_DAILINK_DEF(dummy,
        DAILINK_COMP_ARRAY(COMP_DUMMY()));

expand to:

static struct snd_soc_dai_link_component dummy[] = {
};

Which means that dummy is a zero sized array and thus dais[i].codecs should
not be dereferenced *at all* since it points to the address of the next
variable stored in the data section as the "dummy" variable has an address
but no size, so even dereferencing dais[0] is already an out of bounds
array reference.

Which means that the if (dais[i].codecs->name) check added in
commit 7d99a70b6595 ("ASoC: Intel: Boards: Fix NULL pointer deref
in BYT/CHT boards") relies on that the part of the next variable which
the name member maps to just happens to be NULL.

Which apparently so far it usually is, except when it isn't
and then it results in crashes like this one:

[   28.795659] BUG: unable to handle page fault for address: 0000000000030011
...
[   28.795780] Call Trace:
[   28.795787]  <TASK>
...
[   28.795862]  ? strcmp+0x18/0x40
[   28.795872]  0xffffffffc150c605
[   28.795887]  platform_probe+0x40/0xa0
...
[   28.795979]  ? __pfx_init_module+0x10/0x10 [snd_soc_sst_bytcr_wm5102]

Really fix things this time around by checking dais.num_codecs != 0.

The Linux kernel CVE team has assigned CVE-2024-46793 to this issue.

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

	Issue introduced in 6.8 with commit 7d99a70b6595 and fixed in 6.10.10 with commit 85cda5b040bd
	Issue introduced in 6.8 with commit 7d99a70b6595 and fixed in 6.11 with commit 0cc65482f5b0

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-2024-46793
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/intel/boards/bxt_rt298.c
	sound/soc/intel/boards/bytcht_cx2072x.c
	sound/soc/intel/boards/bytcht_da7213.c
	sound/soc/intel/boards/bytcht_es8316.c
	sound/soc/intel/boards/bytcr_rt5640.c
	sound/soc/intel/boards/bytcr_rt5651.c
	sound/soc/intel/boards/bytcr_wm5102.c
	sound/soc/intel/boards/cht_bsw_rt5645.c
	sound/soc/intel/boards/cht_bsw_rt5672.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/85cda5b040bda9c577b34eb72d5b2e5b7e31985c
	https://git.kernel.org/stable/c/0cc65482f5b03ac2b1c240bc34665e43ea2d71bb