Subject: CVE-2024-49985: i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume

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

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

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

i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume

In case there is any sort of clock controller attached to this I2C bus
controller, for example Versaclock or even an AIC32x4 I2C codec, then
an I2C transfer triggered from the clock controller clk_ops .prepare
callback may trigger a deadlock on drivers/clk/clk.c prepare_lock mutex.

This is because the clock controller first grabs the prepare_lock mutex
and then performs the prepare operation, including its I2C access. The
I2C access resumes this I2C bus controller via .runtime_resume callback,
which calls clk_prepare_enable(), which attempts to grab the prepare_lock
mutex again and deadlocks.

Since the clock are already prepared since probe() and unprepared in
remove(), use simple clk_enable()/clk_disable() calls to enable and
disable the clock on runtime suspend and resume, to avoid hitting the
prepare_lock mutex.

The Linux kernel CVE team has assigned CVE-2024-49985 to this issue.

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

	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 5.10.227 with commit 9b8bc33ad641
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 5.15.168 with commit 1883cad2cc62
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 6.1.113 with commit c2024b1a583a
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 6.6.55 with commit 22a1f8a5b56b
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 6.10.14 with commit fac3c9f7784e
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 6.11.3 with commit 894cd5f5fd90
	Issue introduced in 5.0 with commit 4e7bca6fc07b and fixed in 6.12-rc2 with commit 048bbbdbf85e

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-2024-49985
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/i2c/busses/i2c-stm32f7.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/9b8bc33ad64192f54142396470cc34ce539a8940
	https://git.kernel.org/stable/c/1883cad2cc629ded4a3556c0bbb8b42533ad8764
	https://git.kernel.org/stable/c/c2024b1a583ab9176c797ea1e5f57baf8d5e2682
	https://git.kernel.org/stable/c/22a1f8a5b56ba93d3e8b7a1dafa24e01c8bb48ba
	https://git.kernel.org/stable/c/fac3c9f7784e8184c0338e9f0877b81e55d3ef1c
	https://git.kernel.org/stable/c/894cd5f5fd9061983445bbd1fa3d81be43095344
	https://git.kernel.org/stable/c/048bbbdbf85e5e00258dfb12f5e368f908801d7b