Subject: CVE-2024-36019: regmap: maple: Fix cache corruption in regcache_maple_drop()

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

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

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

regmap: maple: Fix cache corruption in regcache_maple_drop()

When keeping the upper end of a cache block entry, the entry[] array
must be indexed by the offset from the base register of the block,
i.e. max - mas.index.

The code was indexing entry[] by only the register address, leading
to an out-of-bounds access that copied some part of the kernel
memory over the cache contents.

This bug was not detected by the regmap KUnit test because it only
tests with a block of registers starting at 0, so mas.index == 0.

The Linux kernel CVE team has assigned CVE-2024-36019 to this issue.

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

	Issue introduced in 6.4 with commit f033c26de5a5 and fixed in 6.6.26 with commit 3af6c5ac72dc
	Issue introduced in 6.4 with commit f033c26de5a5 and fixed in 6.8.5 with commit 51c4440b9d3f
	Issue introduced in 6.4 with commit f033c26de5a5 and fixed in 6.9 with commit 00bb549d7d63

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-2024-36019
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:
	drivers/base/regmap/regcache-maple.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/3af6c5ac72dc5b721058132a0a1d7779e443175e
	https://git.kernel.org/stable/c/51c4440b9d3fd7c8234e6de9170a487c03506e53
	https://git.kernel.org/stable/c/00bb549d7d63a21532e76e4a334d7807a54d9f31