linux-cve-announce - CVE-2023-53996: x86/sev: Make enc_dec_hypercall() accept a size instead of npages

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Message-ID: <2025122425-CVE-2023-53996-2c23@gregkh>
Date: Wed, 24 Dec 2025 11:56:40 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53996: x86/sev: Make enc_dec_hypercall() accept a size instead of npages

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

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

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

x86/sev: Make enc_dec_hypercall() accept a size instead of npages

enc_dec_hypercall() accepted a page count instead of a size, which
forced its callers to round up. As a result, non-page aligned
vaddrs caused pages to be spuriously marked as decrypted via the
encryption status hypercall, which in turn caused consistent
corruption of pages during live migration. Live migration requires
accurate encryption status information to avoid migrating pages
from the wrong perspective.

The Linux kernel CVE team has assigned CVE-2023-53996 to this issue.


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

	Issue introduced in 5.16 with commit 064ce6c550a0630789978bfec7a13ab2bd1bdcdf and fixed in 6.1.53 with commit ba50e7773a99a109a1ea6f753b766a080d3b21cc
	Issue introduced in 5.16 with commit 064ce6c550a0630789978bfec7a13ab2bd1bdcdf and fixed in 6.4.16 with commit 6615212d8e131b45bd9705b0d69cc0d2f624666f
	Issue introduced in 5.16 with commit 064ce6c550a0630789978bfec7a13ab2bd1bdcdf and fixed in 6.5.3 with commit 8ae7457e71a320867d868f2622d7c643596e4f43
	Issue introduced in 5.16 with commit 064ce6c550a0630789978bfec7a13ab2bd1bdcdf and fixed in 6.6 with commit ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2

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-2023-53996
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/include/asm/mem_encrypt.h
	arch/x86/kernel/kvm.c
	arch/x86/mm/mem_encrypt_amd.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/ba50e7773a99a109a1ea6f753b766a080d3b21cc
	https://git.kernel.org/stable/c/6615212d8e131b45bd9705b0d69cc0d2f624666f
	https://git.kernel.org/stable/c/8ae7457e71a320867d868f2622d7c643596e4f43
	https://git.kernel.org/stable/c/ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2