cve/published/2025/CVE-2025-21689.mbox

From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2025-21689: USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

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

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

USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

This patch addresses a null-ptr-deref in qt2_process_read_urb() due to
an incorrect bounds check in the following:

       if (newport > serial->num_ports) {
               dev_err(&port->dev,
                       "%s - port change to invalid port: %i\n",
                       __func__, newport);
               break;
       }

The condition doesn't account for the valid range of the serial->port
buffer, which is from 0 to serial->num_ports - 1. When newport is equal
to serial->num_ports, the assignment of "port" in the
following code is out-of-bounds and NULL:

       serial_priv->current_port = newport;
       port = serial->port[serial_priv->current_port];

The fix checks if newport is greater than or equal to serial->num_ports
indicating it is out-of-bounds.

The Linux kernel CVE team has assigned CVE-2025-21689 to this issue.


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

	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 5.4.290 with commit fa4c7472469d97c4707698b4c0e098f8cfc2bf22
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 5.10.234 with commit 94770cf7c5124f0268d481886829dc2beecc4507
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 5.15.178 with commit 6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 6.1.128 with commit 4b9b41fabcd38990f69ef0cee9c631d954a2b530
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 6.6.75 with commit 6377838560c03b36e1153a42ef727533def9b68f
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 6.12.12 with commit f371471708c7d997f763b0e70565026eb67cc470
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 6.13.1 with commit 8542b33622571f54dfc2a267fce378b6e3840b8b
	Issue introduced in 3.5 with commit f7a33e608d9ae022b7f49307921627e34e9484ed and fixed in 6.14 with commit 575a5adf48b06a2980c9eeffedf699ed5534fade

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-2025-21689
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/usb/serial/quatech2.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/fa4c7472469d97c4707698b4c0e098f8cfc2bf22
	https://git.kernel.org/stable/c/94770cf7c5124f0268d481886829dc2beecc4507
	https://git.kernel.org/stable/c/6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe
	https://git.kernel.org/stable/c/4b9b41fabcd38990f69ef0cee9c631d954a2b530
	https://git.kernel.org/stable/c/6377838560c03b36e1153a42ef727533def9b68f
	https://git.kernel.org/stable/c/f371471708c7d997f763b0e70565026eb67cc470
	https://git.kernel.org/stable/c/8542b33622571f54dfc2a267fce378b6e3840b8b
	https://git.kernel.org/stable/c/575a5adf48b06a2980c9eeffedf699ed5534fade