linux-cve-announce - CVE-2024-47727: x86/tdx: Fix "in-kernel MMIO" check

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Message-ID: <2024102105-CVE-2024-47727-1049@gregkh>
Date: Mon, 21 Oct 2024 14:16:06 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-47727: x86/tdx: Fix "in-kernel MMIO" check

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

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

x86/tdx: Fix "in-kernel MMIO" check

TDX only supports kernel-initiated MMIO operations. The handle_mmio()
function checks if the #VE exception occurred in the kernel and rejects
the operation if it did not.

However, userspace can deceive the kernel into performing MMIO on its
behalf. For example, if userspace can point a syscall to an MMIO address,
syscall does get_user() or put_user() on it, triggering MMIO #VE. The
kernel will treat the #VE as in-kernel MMIO.

Ensure that the target MMIO address is within the kernel before decoding
instruction.

The Linux kernel CVE team has assigned CVE-2024-47727 to this issue.


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

	Issue introduced in 5.19 with commit 31d58c4e557d and fixed in 6.1.113 with commit 25703a3c980e
	Issue introduced in 5.19 with commit 31d58c4e557d and fixed in 6.6.54 with commit 4c0c5dcb5471
	Issue introduced in 5.19 with commit 31d58c4e557d and fixed in 6.10.13 with commit 18ecd5b74682
	Issue introduced in 5.19 with commit 31d58c4e557d and fixed in 6.11.2 with commit bca2e29f7e26
	Issue introduced in 5.19 with commit 31d58c4e557d and fixed in 6.12-rc1 with commit d4fc4d014715

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-2024-47727
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/coco/tdx/tdx.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/25703a3c980e21548774eea8c8a87a75c5c8f58c
	https://git.kernel.org/stable/c/4c0c5dcb5471de5fc8f0a1c4980e5815339e1cee
	https://git.kernel.org/stable/c/18ecd5b74682839e7cdafb7cd1ec106df7baa18c
	https://git.kernel.org/stable/c/bca2e29f7e26ce7c3522f8b324c0bd85612f68e3
	https://git.kernel.org/stable/c/d4fc4d01471528da8a9797a065982e05090e1d81