CVE-2026-80642: liveupdate: Reference count incoming FLB data

CVE-2026-80642: liveupdate: Reference count incoming FLB data

[Greg Kroah-Hartman]

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

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

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

liveupdate: Reference count incoming FLB data

Increment the incoming FLB refcount in liveupdate_flb_get_incoming() so
that the FLB structure cannot be freed while the caller is actively using
it. Add an additional liveupdate_flb_put_incoming() function so the
caller can explicitly indicate when it is done using the FLB data.

During a Live Update, a subsystem might need to hold onto the incoming
File-Lifecycle-Bound (FLB) data for an extended period, such as during
device enumeration. Incrementing the reference count guarantees that the
data remains valid and accessible until the subsystem releases it,
preventing future use-after-free bugs.

The Linux kernel CVE team has assigned CVE-2026-80642 to this issue.


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

	Issue introduced in 7.0 with commit cab056f2aae7250af50e503b81a80dfc567a1acd and fixed in 7.1.5 with commit 725ada0273a0f48a67fd59cc518d7f8055fe3d5c
	Issue introduced in 7.0 with commit cab056f2aae7250af50e503b81a80dfc567a1acd and fixed in 7.2 with commit d8e47bd066d7e626f9f45d416182d585b7e18b9b

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-2026-80642
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:
	include/linux/liveupdate.h
	kernel/liveupdate/luo_flb.c
	lib/tests/liveupdate.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/725ada0273a0f48a67fd59cc518d7f8055fe3d5c
	https://git.kernel.org/stable/c/d8e47bd066d7e626f9f45d416182d585b7e18b9b