linux-cve-announce - CVE-2025-38071: x86/mm: Check return value from memblock_phys_alloc

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Message-ID: <2025061838-CVE-2025-38071-cc7c@gregkh>
Date: Wed, 18 Jun 2025 11:34:06 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38071: x86/mm: Check return value from memblock_phys_alloc_range()

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

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

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

x86/mm: Check return value from memblock_phys_alloc_range()

At least with CONFIG_PHYSICAL_START=0x100000, if there is < 4 MiB of
contiguous free memory available at this point, the kernel will crash
and burn because memblock_phys_alloc_range() returns 0 on failure,
which leads memblock_phys_free() to throw the first 4 MiB of physical
memory to the wolves.

At a minimum it should fail gracefully with a meaningful diagnostic,
but in fact everything seems to work fine without the weird reserve
allocation.

The Linux kernel CVE team has assigned CVE-2025-38071 to this issue.


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

	Fixed in 6.1.141 with commit 8c18c904d301ffeb33b071eadc55cd6131e1e9be
	Fixed in 6.6.93 with commit bffd5f2815c5234d609725cd0dc2f4bc5de2fc67
	Fixed in 6.12.31 with commit c6f2694c580c27dca0cf7546ee9b4bfa6b940e38
	Fixed in 6.14.9 with commit dde4800d2b0f68b945fd81d4fc2d4a10ae25f743
	Fixed in 6.15 with commit 631ca8909fd5c62b9fda9edda93924311a78a9c4

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-2025-38071
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/x86/mm/init.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/8c18c904d301ffeb33b071eadc55cd6131e1e9be
	https://git.kernel.org/stable/c/bffd5f2815c5234d609725cd0dc2f4bc5de2fc67
	https://git.kernel.org/stable/c/c6f2694c580c27dca0cf7546ee9b4bfa6b940e38
	https://git.kernel.org/stable/c/dde4800d2b0f68b945fd81d4fc2d4a10ae25f743
	https://git.kernel.org/stable/c/631ca8909fd5c62b9fda9edda93924311a78a9c4