CVE-2026-81011: platform/x86: hp-bioscfg: pass validated element count to package parsers

CVE-2026-81011: platform/x86: hp-bioscfg: pass validated element count to package parsers

[Greg Kroah-Hartman]

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

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

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

platform/x86: hp-bioscfg: pass validated element count to package parsers

The per-type package parsers are handed the wrong element count.

hp_init_bios_package_attribute() validates obj->package.count and then
calls one of the five hp_populate_*_package_data() wrappers (string,
integer, enumeration, ordered list, password). Each wrapper forwards a
count to its hp_populate_*_elements_from_package() parser, but instead
of forwarding the validated obj->package.count it derives the count
from elements[0]. elements[0] is the NAME field and is always an
ACPI_TYPE_STRING, so reading ->package.count from it in fact reads
->string.length through the union acpi_object. The parsers thus bound
themselves against the length of the name string rather than against
the real number of elements in the package.

This is safe today because hp_init_bios_package_attribute() refuses any
package that has fewer than the type's element count, so a parser only
ever runs on a full package and never reads past it regardless of the
bogus bound.

An upcoming change relaxes that check to accept shorter packages. Once
a parser can receive fewer elements than its per-type count, a bound
taken from the name length no longer reflects the array size, and the
"elem < count" loop conditions and "elem + n >= count" sub-loop guards
read past the end of elements[] - an out-of-bounds heap read.

Forward the validated obj->package.count to every *_package_data()
wrapper so the parsers bound themselves against the real package size.
This does not change behaviour for the packages that enumerate
correctly today and is a prerequisite for accepting shorter packages
safely.

The Linux kernel CVE team has assigned CVE-2026-81011 to this issue.


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

	Fixed in 6.12.109 with commit 436017808c7cbcdb5e49b2142090d4391e3de9a6
	Fixed in 6.18.50 with commit a38127df99ae8b1851560b35b837c9952416143a
	Fixed in 7.2.4 with commit 400cbc3ccc88a5ad37cd85056224635ce9eba018
	Fixed in 7.3-rc1 with commit e0ddfd77c0c320b7d12b6c9169303b140b798775

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-2026-81011
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/platform/x86/hp/hp-bioscfg/bioscfg.c
	drivers/platform/x86/hp/hp-bioscfg/bioscfg.h
	drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c
	drivers/platform/x86/hp/hp-bioscfg/int-attributes.c
	drivers/platform/x86/hp/hp-bioscfg/order-list-attributes.c
	drivers/platform/x86/hp/hp-bioscfg/passwdobj-attributes.c
	drivers/platform/x86/hp/hp-bioscfg/string-attributes.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/436017808c7cbcdb5e49b2142090d4391e3de9a6
	https://git.kernel.org/stable/c/a38127df99ae8b1851560b35b837c9952416143a
	https://git.kernel.org/stable/c/400cbc3ccc88a5ad37cd85056224635ce9eba018
	https://git.kernel.org/stable/c/e0ddfd77c0c320b7d12b6c9169303b140b798775