CVE-2026-98754: tty: vcc: hold port lock when clearing tty pointer in vcc_cleanup

CVE-2026-98754: tty: vcc: hold port lock when clearing tty pointer in vcc_cleanup

[Greg Kroah-Hartman]

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

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

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

tty: vcc: hold port lock when clearing tty pointer in vcc_cleanup

vcc_cleanup() sets port->tty to NULL without holding port->lock, racing
with vcc_event() LDC callbacks that read port->tty under port->lock and
then use tty->port. This can cause a use-after-free when the callback
dereferences tty->port after cleanup has already destroyed and freed it.

The Linux kernel CVE team has assigned CVE-2026-98754 to this issue.


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

	Fixed in 6.12.113 with commit 88f6ecb058801e9ce7b9aabc966530118d7cd53c
	Fixed in 6.18.56 with commit 821050631750e982007c0856c119346edba51cae
	Fixed in 7.2.10 with commit 1a9fb9eaeb69b1f6c00bed09289a33d9fe1e7ae4
	Fixed in 7.3-rc6 with commit 03b49c991abb8d021ca6fe51cd173447236b0552

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-2026-98754
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/vcc.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/88f6ecb058801e9ce7b9aabc966530118d7cd53c
	https://git.kernel.org/stable/c/821050631750e982007c0856c119346edba51cae
	https://git.kernel.org/stable/c/1a9fb9eaeb69b1f6c00bed09289a33d9fe1e7ae4
	https://git.kernel.org/stable/c/03b49c991abb8d021ca6fe51cd173447236b0552