CVE-2026-53020: um: Fix potential race condition in TLB sync

CVE-2026-53020: um: Fix potential race condition in TLB sync

[Greg Kroah-Hartman]

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

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

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

um: Fix potential race condition in TLB sync

During the TLB sync, we need to traverse and modify the page table,
so we should hold the page table lock. Since full SMP support for
threads within the same process is still missing, let's disable the
split page table lock for simplicity.

The Linux kernel CVE team has assigned CVE-2026-53020 to this issue.


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

	Issue introduced in 6.19 with commit 1e4ee5135d814fe4785890790cec81c3132888fb and fixed in 7.0.10 with commit f21c343ec7419377bff89ab11146c03ae117036f
	Issue introduced in 6.19 with commit 1e4ee5135d814fe4785890790cec81c3132888fb and fixed in 7.1 with commit 102331b66bcaf1f41f50b9c4cd5c36e46bafa9f3

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-2026-53020
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:
	arch/um/kernel/tlb.c
	mm/Kconfig


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/f21c343ec7419377bff89ab11146c03ae117036f
	https://git.kernel.org/stable/c/102331b66bcaf1f41f50b9c4cd5c36e46bafa9f3