Subject: CVE-2024-26716: usb: core: Prevent null pointer dereference in update_port_device_state

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

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

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

usb: core: Prevent null pointer dereference in update_port_device_state

Currently, the function update_port_device_state gets the usb_hub from
udev->parent by calling usb_hub_to_struct_hub.
However, in case the actconfig or the maxchild is 0, the usb_hub would
be NULL and upon further accessing to get port_dev would result in null
pointer dereference.

Fix this by introducing an if check after the usb_hub is populated.

The Linux kernel CVE team has assigned CVE-2024-26716 to this issue.

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

	Issue introduced in 6.5 with commit 83cb2604f641 and fixed in 6.6.18 with commit ed85777c640c
	Issue introduced in 6.5 with commit 83cb2604f641 and fixed in 6.7.6 with commit 465b545d1d7e
	Issue introduced in 6.5 with commit 83cb2604f641 and fixed in 6.8 with commit 12783c0b9e2c

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-2024-26716
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/core/hub.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/ed85777c640cf9e6920bb1b60ed8cd48e1f4d873
	https://git.kernel.org/stable/c/465b545d1d7ef282192ddd4439b08279bdb13f6f
	https://git.kernel.org/stable/c/12783c0b9e2c7915a50d5ec829630ff2da50472c