CVE-2026-89588: ACPI: APEI: GHES: fix ARM section length accounting after header

CVE-2026-89588: ACPI: APEI: GHES: fix ARM section length accounting after header

[Greg Kroah-Hartman]

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

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

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

ACPI: APEI: GHES: fix ARM section length accounting after header

In ghes_handle_arm_hw_error(), after skipping the cper_sec_proc_arm
header with (err + 1), the remaining length was reduced by sizeof(err)
(pointer size) instead of sizeof(*err) (structure size).

That overestimates the bytes left for cper_arm_err_info records and can
let the parser read past the CPER section when err_info_num is large
enough relative to error_data_length.

Use sizeof(*err) so the length accounting matches the pointer advance
and the earlier sizeof(*err) size check.

The Linux kernel CVE team has assigned CVE-2026-89588 to this issue.


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

	Issue introduced in 6.12.75 with commit 242c652849d979d0133c315a42d9acea0ff88390 and fixed in 6.12.109 with commit 5ff385e9403e87ae33f65b8c38698d3b1e92cfde
	Issue introduced in 6.18.16 with commit 136093ba4161e0080088abff48273f6830a47766 and fixed in 6.18.50 with commit 452eb28e03015abec6d4bf6488ee567706ade4e1
	Issue introduced in 7.0 with commit 87880af2d24e62a84ed19943dbdd524f097172f2 and fixed in 7.2.4 with commit b48b613073c3d652cb1823c15d16f7067cf4cee4
	Issue introduced in 7.0 with commit 87880af2d24e62a84ed19943dbdd524f097172f2 and fixed in 7.3-rc1 with commit 903308ea40adf0577d82eab69882faf8836326ce
	Issue introduced in 6.19.6 with commit db103b8bd3a4aca69b1b5fe8831a6ed75ac4b3bd

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-2026-89588
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/acpi/apei/ghes.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/5ff385e9403e87ae33f65b8c38698d3b1e92cfde
	https://git.kernel.org/stable/c/452eb28e03015abec6d4bf6488ee567706ade4e1
	https://git.kernel.org/stable/c/b48b613073c3d652cb1823c15d16f7067cf4cee4
	https://git.kernel.org/stable/c/903308ea40adf0577d82eab69882faf8836326ce