linux-cve-announce - CVE-2024-27007: userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO

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Date: Wed,  1 May 2024 07:31:08 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-27007: userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE

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

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

userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE

Commit d7a08838ab74 ("mm: userfaultfd: fix unexpected change to src_folio
when UFFDIO_MOVE fails") moved the src_folio->{mapping, index} changing to
after clearing the page-table and ensuring that it's not pinned.  This
avoids failure of swapout+migration and possibly memory corruption.

However, the commit missed fixing it in the huge-page case.

The Linux kernel CVE team has assigned CVE-2024-27007 to this issue.


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

	Issue introduced in 6.8 with commit adef440691ba and fixed in 6.8.8 with commit df5f6e683e7f
	Issue introduced in 6.8 with commit adef440691ba and fixed in 6.9-rc5 with commit c0205eaf3af9

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-2024-27007
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:
	mm/huge_memory.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/df5f6e683e7f21a15d8be6e7a0c7a46436963ebe
	https://git.kernel.org/stable/c/c0205eaf3af9f5db14d4b5ee4abacf4a583c3c50