linux-cve-announce - CVE-2023-54212: ALSA: pcm: Move rwsem lock inside snd_ctl_elem

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Message-ID: <2025123024-CVE-2023-54212-dc0b@gregkh>
Date: Tue, 30 Dec 2025 13:13:42 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54212: ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF

[ Note: this is a fix that works around the bug equivalently as the
  two upstream commits:
   1fa4445f9adf ("ALSA: control - introduce snd_ctl_notify_one() helper")
   56b88b50565c ("ALSA: pcm: Move rwsem lock inside snd_ctl_elem_read to prevent UAF")
  but in a simpler way to fit with older stable trees -- tiwai ]

Add missing locking in ctl_elem_read_user/ctl_elem_write_user which can be
easily triggered and turned into an use-after-free.

Example code paths with SNDRV_CTL_IOCTL_ELEM_READ:

64-bits:
snd_ctl_ioctl
  snd_ctl_elem_read_user
    [takes controls_rwsem]
    snd_ctl_elem_read [lock properly held, all good]
    [drops controls_rwsem]

32-bits (compat):
snd_ctl_ioctl_compat
  snd_ctl_elem_write_read_compat
    ctl_elem_write_read
      snd_ctl_elem_read [missing lock, not good]

CVE-2023-0266 was assigned for this issue.

The Linux kernel CVE team has assigned CVE-2023-54212 to this issue.


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

	Fixed in 5.10.163 with commit df02234e6b87d2a9a82acd3198e44bdeff8488c6

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-2023-54212
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/core/control_compat.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/df02234e6b87d2a9a82acd3198e44bdeff8488c6