linux-cve-announce - CVE-2025-37996: KVM: arm64: Fix uninitialized memcache pointer in user_mem

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Message-ID: <2025052902-CVE-2025-37996-0018@gregkh>
Date: Thu, 29 May 2025 15:16:03 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37996: KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()

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

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

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

KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()

Commit fce886a60207 ("KVM: arm64: Plumb the pKVM MMU in KVM") made the
initialization of the local memcache variable in user_mem_abort()
conditional, leaving a codepath where it is used uninitialized via
kvm_pgtable_stage2_map().

This can fail on any path that requires a stage-2 allocation
without transition via a permission fault or dirty logging.

Fix this by making sure that memcache is always valid.

The Linux kernel CVE team has assigned CVE-2025-37996 to this issue.


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

	Issue introduced in 6.14 with commit fce886a6020734d6253c2c5a3bc285e385cc5496 and fixed in 6.14.7 with commit a26d50f8a4a5049e956984797b5d0dedea4bbb18
	Issue introduced in 6.14 with commit fce886a6020734d6253c2c5a3bc285e385cc5496 and fixed in 6.15 with commit 157dbc4a321f5bb6f8b6c724d12ba720a90f1a7c

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-2025-37996
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/arm64/kvm/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/a26d50f8a4a5049e956984797b5d0dedea4bbb18
	https://git.kernel.org/stable/c/157dbc4a321f5bb6f8b6c724d12ba720a90f1a7c