Subject: CVE-2021-47046: drm/amd/display: Fix off by one in hdmi_14_process_transaction()

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

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

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

drm/amd/display: Fix off by one in hdmi_14_process_transaction()

The hdcp_i2c_offsets[] array did not have an entry for
HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE so it led to an off by one
read overflow.  I added an entry and copied the 0x0 value for the offset
from similar code in drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c.

I also declared several of these arrays as having HDCP_MESSAGE_ID_MAX
entries.  This doesn't change the code, but it's just a belt and
suspenders approach to try future proof the code.

The Linux kernel CVE team has assigned CVE-2021-47046 to this issue.

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

	Issue introduced in 5.5 with commit 4c283fdac08a and fixed in 5.10.37 with commit 403c4528e588
	Issue introduced in 5.5 with commit 4c283fdac08a and fixed in 5.11.21 with commit 6a58310d5d1e
	Issue introduced in 5.5 with commit 4c283fdac08a and fixed in 5.12.4 with commit 080bd41d6478
	Issue introduced in 5.5 with commit 4c283fdac08a and fixed in 5.13 with commit 8e6fafd5a22e

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-2021-47046
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/amd/display/dc/hdcp/hdcp_msg.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/403c4528e5887af3deb9838cb77a557631d1e138
	https://git.kernel.org/stable/c/6a58310d5d1e5b02d0fc9b393ba540c9367bced5
	https://git.kernel.org/stable/c/080bd41d6478a64edf96704fddcda52b1fd5fed7
	https://git.kernel.org/stable/c/8e6fafd5a22e7a2eb216f5510db7aab54cc545c1