CVE-2026-80663: tools/power/x86/intel-speed-select: Harden daemon pidfile open

CVE-2026-80663: tools/power/x86/intel-speed-select: Harden daemon pidfile open

[Greg Kroah-Hartman]

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

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

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

tools/power/x86/intel-speed-select: Harden daemon pidfile open

Avoid symlink-based pidfile clobbering by opening the pidfile with
O_NOFOLLOW and validating it with fstat() before locking/writing.

The daemon currently uses a fixed pidfile path under /tmp. A local
unprivileged user can pre-create a symlink at that path and cause a
root-run daemon instance to write into an attacker-chosen file.

The Linux kernel CVE team has assigned CVE-2026-80663 to this issue.


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

	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 6.1.178 with commit 905493a6338c82a70da16f86e0a6215db5a3d73d
	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 6.6.145 with commit db938eb9a3c1317596c28e94413b33426508d51b
	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 6.12.97 with commit 72a07abc6b9046f07a08bba353cad7667bcc9dce
	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 6.18.40 with commit 19ffeb30fdfce63f8d6aca71bcdddb3f69d46278
	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 7.1.5 with commit e8adac69d1bdf035ef97cc914e845acd4ef08e28
	Issue introduced in 5.18 with commit 7fd786dfbd2c55ddee3b87f33c82f1c58bdb1dd6 and fixed in 7.2 with commit 607af438e6430893a822964c841a1994b33acccc

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-2026-80663
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:
	tools/power/x86/intel-speed-select/isst-daemon.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/905493a6338c82a70da16f86e0a6215db5a3d73d
	https://git.kernel.org/stable/c/db938eb9a3c1317596c28e94413b33426508d51b
	https://git.kernel.org/stable/c/72a07abc6b9046f07a08bba353cad7667bcc9dce
	https://git.kernel.org/stable/c/19ffeb30fdfce63f8d6aca71bcdddb3f69d46278
	https://git.kernel.org/stable/c/e8adac69d1bdf035ef97cc914e845acd4ef08e28
	https://git.kernel.org/stable/c/607af438e6430893a822964c841a1994b33acccc