CVE-2026-80749: drm/connector/hdmi: Fix out of bounds memory read

CVE-2026-80749: drm/connector/hdmi: Fix out of bounds memory read

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

drm/connector/hdmi: Fix out of bounds memory read

A helper function was copying a given audio infoframe into the
connector's copy but using the size of the destination (a generic
target, sized to accept many different data blocks) not the source (a
very specific type of data block). Thus, it was copying 60 bytes of
data from a 28 byte allocation.

Fix that by using the source size instead, together with a build bug
on the source size actually being smaller than the destination.

I hit this running KUnit tests under KASAN (while debugging something
else entirely). In the real world, it seems unlikely to cause an
actual problem. It is a read not a write so it can't corrupt any
memory. However, it could potentially fall off the end of a page and
cause an accvio bug.

The Linux kernel CVE team has assigned CVE-2026-80749 to this issue.


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

	Issue introduced in 6.11 with commit f378b77227bc4732922c57f92be89438bb1018a1 and fixed in 6.12.105 with commit d9f7454c185c0c7f0973e11d62ad6c06862c324c
	Issue introduced in 6.11 with commit f378b77227bc4732922c57f92be89438bb1018a1 and fixed in 6.18.46 with commit e5b527804a1ea4f70e139179d3062cf5de8c06ab
	Issue introduced in 6.11 with commit f378b77227bc4732922c57f92be89438bb1018a1 and fixed in 7.1.10 with commit f72bb95732bc5ca87b50c52c8f087ba501950809
	Issue introduced in 6.11 with commit f378b77227bc4732922c57f92be89438bb1018a1 and fixed in 7.2 with commit 9ecf8ba763d0ffe0673538eb4bf7806f20455d19

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-2026-80749
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/display/drm_hdmi_state_helper.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/d9f7454c185c0c7f0973e11d62ad6c06862c324c
	https://git.kernel.org/stable/c/e5b527804a1ea4f70e139179d3062cf5de8c06ab
	https://git.kernel.org/stable/c/f72bb95732bc5ca87b50c52c8f087ba501950809
	https://git.kernel.org/stable/c/9ecf8ba763d0ffe0673538eb4bf7806f20455d19