Subject: CVE-2024-26617: fs/proc/task_mmu: move mmu notification mechanism inside mm lock

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

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

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

fs/proc/task_mmu: move mmu notification mechanism inside mm lock

Move mmu notification mechanism inside mm lock to prevent race condition
in other components which depend on it.  The notifier will invalidate
memory range.  Depending upon the number of iterations, different memory
ranges would be invalidated.

The following warning would be removed by this patch:
WARNING: CPU: 0 PID: 5067 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 kvm_mmu_notifier_change_pte+0x860/0x960 arch/x86/kvm/../../../virt/kvm/kvm_main.c:734

There is no behavioural and performance change with this patch when
there is no component registered with the mmu notifier.

[[email-masked]: narrow the scope of `range', per Sean]

The Linux kernel CVE team has assigned CVE-2024-26617 to this issue.

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

	Issue introduced in 6.7 with commit 52526ca7fdb9 and fixed in 6.7.3 with commit 05509adf2979
	Issue introduced in 6.7 with commit 52526ca7fdb9 and fixed in 6.8 with commit 4cccb6221cae

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-2024-26617
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:
	fs/proc/task_mmu.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/05509adf297924f51e1493aa86f9fcde1433ed80
	https://git.kernel.org/stable/c/4cccb6221cae6d020270606b9e52b1678fc8b71a