CVE-2020-36778: i2c: xiic: fix reference leak when pm_runtime_get_sync fails

CVE-2020-36778: i2c: xiic: fix reference leak when pm_runtime_get_sync fails

[Greg Kroah-Hartman]

From: gregkh@kernel.org

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

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

i2c: xiic: fix reference leak when pm_runtime_get_sync fails

The PM reference count is not expected to be incremented on
return in xiic_xfer and xiic_i2c_remove.

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-2020-36778 to this issue.


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

	Issue introduced in 5.6 with commit 10b17004a74c and fixed in 5.10.37 with commit c977426db644
	Issue introduced in 5.6 with commit 10b17004a74c and fixed in 5.11.21 with commit e2ba996577ea
	Issue introduced in 5.6 with commit 10b17004a74c and fixed in 5.12.4 with commit a42ac16e6573
	Issue introduced in 5.6 with commit 10b17004a74c and fixed in 5.13 with commit a85c5c7a3aa8

Please see https://www.kernel.org or 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-2020-36778
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-xiic.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/c977426db644ba476938125597947979e8aba725
	https://git.kernel.org/stable/c/e2ba996577eaea423694dc69ae43d56f1410a22b
	https://git.kernel.org/stable/c/a42ac16e6573f19c78f556ea292f5b534fcc4514
	https://git.kernel.org/stable/c/a85c5c7a3aa8041777ff691400b4046e56149fd3