Subject: CVE-2021-47530: drm/msm: Fix wait_fence submitqueue leak

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

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

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

drm/msm: Fix wait_fence submitqueue leak

We weren't dropping the submitqueue reference in all paths.  In
particular, when the fence has already been signalled. Split out
a helper to simplify handling this in the various different return
paths.

The Linux kernel CVE team has assigned CVE-2021-47530 to this issue.

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

	Issue introduced in 5.15 with commit a61acbbe9cf8 and fixed in 5.15.7 with commit 4c3cdbf25403
	Issue introduced in 5.15 with commit a61acbbe9cf8 and fixed in 5.16 with commit ea0006d390a2

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-2021-47530
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/gpu/drm/msm/msm_drv.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/4c3cdbf2540319ea674f1f3c54f31f14c6f39647
	https://git.kernel.org/stable/c/ea0006d390a28012f8187717aea61498b2b341e5