CVE-2026-74675: vt: stabilize tty reference in kbd_keycode with tty_port_tty_get

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

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

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

vt: stabilize tty reference in kbd_keycode with tty_port_tty_get

kbd_keycode() reads vc->port.tty without acquiring a tty reference,
racing against con_shutdown() which clears port.tty under a different
lock. Use tty_port_tty_get()/tty_kref_put() to hold a proper reference
for the duration the tty pointer is needed.

The Linux kernel CVE team has assigned CVE-2026-74675 to this issue.


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

	Fixed in 5.10.265 with commit b84fd400f80adf4d1c88fbce50ae1cf2f8119e65
	Fixed in 5.15.216 with commit 38400673c9bfb39cfc87539e1a072087e98f4e4f
	Fixed in 6.1.183 with commit cab5a342f0589334046741006d8a280514f94235
	Fixed in 6.6.152 with commit 38a0aa593ebc275aea6f79534d07f44e43768ce6
	Fixed in 6.12.104 with commit 3f6b1d3fcfc26dc3fc85262f753439df93b055b4
	Fixed in 6.18.45 with commit b664592e9ba8c47c9e23408db7ba52eb9f946c8a
	Fixed in 7.1.9 with commit cc4a1a2ce0c58eafd477effb055863935260ddc1
	Fixed in 7.2 with commit e25d47a526939ad44b75f778b8a7500562b84fc1

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-2026-74675
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/keyboard.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/b84fd400f80adf4d1c88fbce50ae1cf2f8119e65
	https://git.kernel.org/stable/c/38400673c9bfb39cfc87539e1a072087e98f4e4f
	https://git.kernel.org/stable/c/cab5a342f0589334046741006d8a280514f94235
	https://git.kernel.org/stable/c/38a0aa593ebc275aea6f79534d07f44e43768ce6
	https://git.kernel.org/stable/c/3f6b1d3fcfc26dc3fc85262f753439df93b055b4
	https://git.kernel.org/stable/c/b664592e9ba8c47c9e23408db7ba52eb9f946c8a
	https://git.kernel.org/stable/c/cc4a1a2ce0c58eafd477effb055863935260ddc1
	https://git.kernel.org/stable/c/e25d47a526939ad44b75f778b8a7500562b84fc1