CVE-2026-64111: lsm: hold cred_guard_mutex for lsm_set_self_attr()

From: Greg Kroah-Hartman <[email protected]>

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

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

lsm: hold cred_guard_mutex for lsm_set_self_attr()

Just as proc_pid_attr_write() already does before calling the LSM
hook. This only matters for SELinux and AppArmor which check
whether the process is being ptraced and if so, whether to
allow the transition.

The Linux kernel CVE team has assigned CVE-2026-64111 to this issue.


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

	Fixed in 6.12.92 with commit 82d3acee88593e3d9e71cad4b7d6b3cf70de9d07
	Fixed in 6.18.34 with commit 5b906f31e977286888a9e31282589b545b249139
	Fixed in 7.0.11 with commit a010cadaf5727b8417f62fe9021fcef14a5f9b51
	Fixed in 7.1 with commit 4a9b16541ad3faf8bccb398532bf3f8b6bbf1188

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-2026-64111
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:
	security/lsm_syscalls.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/82d3acee88593e3d9e71cad4b7d6b3cf70de9d07
	https://git.kernel.org/stable/c/5b906f31e977286888a9e31282589b545b249139
	https://git.kernel.org/stable/c/a010cadaf5727b8417f62fe9021fcef14a5f9b51
	https://git.kernel.org/stable/c/4a9b16541ad3faf8bccb398532bf3f8b6bbf1188