Subject: CVE-2021-47286: bus: mhi: core: Validate channel ID when processing command completions

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

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

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

bus: mhi: core: Validate channel ID when processing command completions

MHI reads the channel ID from the event ring element sent by the
device which can be any value between 0 and 255. In order to
prevent any out of bound accesses, add a check against the maximum
number of channels supported by the controller and those channels
not configured yet so as to skip processing of that event ring
element.

The Linux kernel CVE team has assigned CVE-2021-47286 to this issue.

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

	Issue introduced in 5.7 with commit 1d3173a3bae7 and fixed in 5.10.54 with commit 3efec3b4b16f
	Issue introduced in 5.7 with commit 1d3173a3bae7 and fixed in 5.13.6 with commit aed4f5b51aba
	Issue introduced in 5.7 with commit 1d3173a3bae7 and fixed in 5.14 with commit 546362a9ef2e

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-2021-47286
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/bus/mhi/core/main.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/3efec3b4b16fc7af25676a94230a8ab2a3bb867c
	https://git.kernel.org/stable/c/aed4f5b51aba41e2afd7cfda20a0571a6a67dfe9
	https://git.kernel.org/stable/c/546362a9ef2ef40b57c6605f14e88ced507f8dd0