CVE-2026-74676: vt: add permission check for KDSKBMETA ioctl

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

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

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

vt: add permission check for KDSKBMETA ioctl

KDSKBMETA modifies keyboard meta mode but lacks the !perm check that all
other keyboard setter ioctls in vt_k_ioctl() enforce, allowing a process
to change meta mode on a non-controlling console without authorization.

The Linux kernel CVE team has assigned CVE-2026-74676 to this issue.


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

	Fixed in 5.10.265 with commit 9f8cbaf4b774694dcc292e60509762483ebfd9ae
	Fixed in 5.15.216 with commit ddc4a8303347114e945b9e6e81b81d77855f7358
	Fixed in 6.1.183 with commit 1c5b67a1e2cb7d78dab321280f330b056e3bf437
	Fixed in 6.6.152 with commit d8ead5083b203d12b8319e7cb29cc6b8836e813f
	Fixed in 6.12.104 with commit 4671c3b79e337bbae28c2d79023dc642df012bde
	Fixed in 6.18.45 with commit a1c31e026c93e378e297a8df8328983d3013a59f
	Fixed in 7.1.9 with commit 7bf32337a7103ccb686cbd240324bf26225ef2d6
	Fixed in 7.2 with commit a7ad0034453ba4c353f9b8f810ee2569de33d283

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-2026-74676
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/tty/vt/vt_ioctl.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/9f8cbaf4b774694dcc292e60509762483ebfd9ae
	https://git.kernel.org/stable/c/ddc4a8303347114e945b9e6e81b81d77855f7358
	https://git.kernel.org/stable/c/1c5b67a1e2cb7d78dab321280f330b056e3bf437
	https://git.kernel.org/stable/c/d8ead5083b203d12b8319e7cb29cc6b8836e813f
	https://git.kernel.org/stable/c/4671c3b79e337bbae28c2d79023dc642df012bde
	https://git.kernel.org/stable/c/a1c31e026c93e378e297a8df8328983d3013a59f
	https://git.kernel.org/stable/c/7bf32337a7103ccb686cbd240324bf26225ef2d6
	https://git.kernel.org/stable/c/a7ad0034453ba4c353f9b8f810ee2569de33d283