Subject: CVE-2020-36779: i2c: stm32f7: fix reference leak when pm_runtime_get_sync fails

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

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

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

i2c: stm32f7: fix reference leak when pm_runtime_get_sync fails

The PM reference count is not expected to be incremented on
return in these stm32f7_i2c_xx serious functions.

However, pm_runtime_get_sync will increment the PM reference
count even failed. Forgetting to putting operation will result
in a reference leak here.

Replace it with pm_runtime_resume_and_get to keep usage
counter balanced.

The Linux kernel CVE team has assigned CVE-2020-36779 to this issue.

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

	Issue introduced in 5.6 with commit ea6dd25deeb5 and fixed in 5.10.37 with commit c323b270a52a
	Issue introduced in 5.6 with commit ea6dd25deeb5 and fixed in 5.11.21 with commit d791b90f5c5e
	Issue introduced in 5.6 with commit ea6dd25deeb5 and fixed in 5.12.4 with commit c7ea772c9fcf
	Issue introduced in 5.6 with commit ea6dd25deeb5 and fixed in 5.13 with commit 2c662660ce2b

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-2020-36779
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/c323b270a52a26aa8038a4d1fd9a850904a41166
	https://git.kernel.org/stable/c/d791b90f5c5e5aa8ccf9e33386c16bd2b7e333a4
	https://git.kernel.org/stable/c/c7ea772c9fcf711ed566814b92eecaffc0e2bfd0
	https://git.kernel.org/stable/c/2c662660ce2bd3b09dae21a9a9ac9395e1e6c00b