CVE-2026-80965: ALSA: serial-u16550: Check card index validity at probe

CVE-2026-80965: ALSA: serial-u16550: Check card index validity at probe

[Greg Kroah-Hartman]

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

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

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

ALSA: serial-u16550: Check card index validity at probe

serial-u16550 driver blindly trusts that the given devptr->id value is
within the proper card index range at probe.  It's OK for the devices
the driver itself creates at the module probe time, but if the device
is bound manually via sysfs interface, this could be -1 as "none", and
this leads to OOB access for index[] and other parameters.

Add a sanity check for the card index and warn/correct it if it's a
value out of the range.

The Linux kernel CVE team has assigned CVE-2026-80965 to this issue.


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

	Fixed in 6.12.109 with commit fbf3fb097e66fc1874e54ecc46d600d9325480d6
	Fixed in 6.18.50 with commit 7555e83d7738e65dc83921e3c85bbdc081f08f2f
	Fixed in 7.2.4 with commit 6d6fdb24fe2eaf6174fc502284c6e1dc5f7242ba
	Fixed in 7.3-rc1 with commit e0fb960b227fcdebe22e4f26c9486d60943c0424

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-2026-80965
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:
	sound/drivers/serial-u16550.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/fbf3fb097e66fc1874e54ecc46d600d9325480d6
	https://git.kernel.org/stable/c/7555e83d7738e65dc83921e3c85bbdc081f08f2f
	https://git.kernel.org/stable/c/6d6fdb24fe2eaf6174fc502284c6e1dc5f7242ba
	https://git.kernel.org/stable/c/e0fb960b227fcdebe22e4f26c9486d60943c0424