CVE-2026-72027: mm/compaction: handle free_pages_prepare() properly in compaction_free()

CVE-2026-72027: mm/compaction: handle free_pages_prepare() properly in compaction_free()

[Greg Kroah-Hartman]

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

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

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

mm/compaction: handle free_pages_prepare() properly in compaction_free()

free_pages_prepare() can fail but compaction_free() does not handle the
failure case.  Failed pages should not be added back to cc->freepages for
future use, since they can be either PageHWPoison or free_page_is_bad()
and might cause data corruption.

The Linux kernel CVE team has assigned CVE-2026-72027 to this issue.


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

	Issue introduced in 6.9 with commit 733aea0b3a7bba0451dfc19322665de13a5b7af4 and fixed in 6.12.97 with commit de8577db09039d4950239b01446ab5ead9028ab4
	Issue introduced in 6.9 with commit 733aea0b3a7bba0451dfc19322665de13a5b7af4 and fixed in 6.18.40 with commit 018d7ad26cb8bdfe9842f2ca68a42b0bfdcc82fe
	Issue introduced in 6.9 with commit 733aea0b3a7bba0451dfc19322665de13a5b7af4 and fixed in 7.1.5 with commit 23afc3786acf359c135093893fb43a436768c832
	Issue introduced in 6.9 with commit 733aea0b3a7bba0451dfc19322665de13a5b7af4 and fixed in 7.2-rc3 with commit 7da7d599b8a83271c464adfd5ef160202b470570

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-2026-72027
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/compaction.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/de8577db09039d4950239b01446ab5ead9028ab4
	https://git.kernel.org/stable/c/018d7ad26cb8bdfe9842f2ca68a42b0bfdcc82fe
	https://git.kernel.org/stable/c/23afc3786acf359c135093893fb43a436768c832
	https://git.kernel.org/stable/c/7da7d599b8a83271c464adfd5ef160202b470570