CVE-2026-89442: platform/x86: ISST: Validate socket ID in clos_assoc ioctl

CVE-2026-89442: platform/x86: ISST: Validate socket ID in clos_assoc ioctl

[Greg Kroah-Hartman]

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

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

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

platform/x86: ISST: Validate socket ID in clos_assoc ioctl

isst_if_clos_assoc() validates the user-supplied socket_id with
'socket_id > topology_max_packages()', but isst_common.sst_inst[] is
allocated with topology_max_packages() entries, so the valid index range
is [0, topology_max_packages()).  The '>' comparison lets
socket_id == topology_max_packages() pass and index one entry past the
array.

In addition, isst_common.sst_inst[socket_id] is NULL for an in-range
package that has no bound TPMI SST instance, and the pointer is used
without a NULL check.  Both the out-of-bounds entry and the NULL pointer
are then dereferenced by map_partition_power_domain_id() and the
following power_domain_info access.

Reject socket_id >= topology_max_packages() and a NULL sst_inst, matching
the checks already performed by get_instance().

The Linux kernel CVE team has assigned CVE-2026-89442 to this issue.


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

	Issue introduced in 6.4 with commit 12a7d2cb811dd8a884dea088a2701fcb8d00136e and fixed in 6.12.109 with commit 0d90ab5f80e19cddfeb0c9fab47a1f34aa932075
	Issue introduced in 6.4 with commit 12a7d2cb811dd8a884dea088a2701fcb8d00136e and fixed in 6.18.50 with commit 82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca
	Issue introduced in 6.4 with commit 12a7d2cb811dd8a884dea088a2701fcb8d00136e and fixed in 7.2.4 with commit 207b4dc6eb100141b122b2602504a1429a4b6558
	Issue introduced in 6.4 with commit 12a7d2cb811dd8a884dea088a2701fcb8d00136e and fixed in 7.3-rc1 with commit a89f07db0cb95c54dac4a8406c79a04e44a73c3c

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-2026-89442
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/intel/speed_select_if/isst_tpmi_core.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/0d90ab5f80e19cddfeb0c9fab47a1f34aa932075
	https://git.kernel.org/stable/c/82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca
	https://git.kernel.org/stable/c/207b4dc6eb100141b122b2602504a1429a4b6558
	https://git.kernel.org/stable/c/a89f07db0cb95c54dac4a8406c79a04e44a73c3c