Subject: CVE-2023-52596: sysctl: Fix out of bounds access for empty sysctl registers

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

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

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

sysctl: Fix out of bounds access for empty sysctl registers

When registering tables to the sysctl subsystem there is a check to see
if header is a permanently empty directory (used for mounts). This check
evaluates the first element of the ctl_table. This results in an out of
bounds evaluation when registering empty directories.

The function register_sysctl_mount_point now passes a ctl_table of size
1 instead of size 0. It now relies solely on the type to identify
a permanently empty register.

Make sure that the ctl_table has at least one element before testing for
permanent emptiness.

The Linux kernel CVE team has assigned CVE-2023-52596 to this issue.

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

	Fixed in 6.6.16 with commit 15893975e9e3
	Fixed in 6.7.4 with commit 2ae7081bc101
	Fixed in 6.8 with commit 315552310c7d

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-2023-52596
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:
	fs/proc/proc_sysctl.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/15893975e9e382f8294ea8d926f08dc2d8d39ede
	https://git.kernel.org/stable/c/2ae7081bc10123b187e36a4f3a8e53768de31489
	https://git.kernel.org/stable/c/315552310c7de92baea4e570967066569937a843