linux-cve-announce - CVE-2024-49858: efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption

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Message-ID: <2024102123-CVE-2024-49858-b7c4@gregkh>
Date: Mon, 21 Oct 2024 14:27:24 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-49858: efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption

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

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

efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption

The TPM event log table is a Linux specific construct, where the data
produced by the GetEventLog() boot service is cached in memory, and
passed on to the OS using an EFI configuration table.

The use of EFI_LOADER_DATA here results in the region being left
unreserved in the E820 memory map constructed by the EFI stub, and this
is the memory description that is passed on to the incoming kernel by
kexec, which is therefore unaware that the region should be reserved.

Even though the utility of the TPM2 event log after a kexec is
questionable, any corruption might send the parsing code off into the
weeds and crash the kernel. So let's use EFI_ACPI_RECLAIM_MEMORY
instead, which is always treated as reserved by the E820 conversion
logic.

The Linux kernel CVE team has assigned CVE-2024-49858 to this issue.

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

	Fixed in 5.10.227 with commit f76b69ab9cf0
	Fixed in 5.15.168 with commit 11690d7e7684
	Fixed in 6.1.113 with commit 5b22c038fb27
	Fixed in 6.6.54 with commit 19fd2f2c5fb3
	Fixed in 6.10.13 with commit 38d9b07d99b7
	Fixed in 6.11.2 with commit 2e6871a632a9
	Fixed in 6.12-rc1 with commit 77d48d39e991

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-2024-49858
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:
	drivers/firmware/efi/libstub/tpm.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/f76b69ab9cf04358266e3cea5748c0c2791fbb08
	https://git.kernel.org/stable/c/11690d7e76842f29b60fbb5b35bc97d206ea0e83
	https://git.kernel.org/stable/c/5b22c038fb2757c652642933de5664da471f8cb7
	https://git.kernel.org/stable/c/19fd2f2c5fb36b61506d3208474bfd8fdf1cada3
	https://git.kernel.org/stable/c/38d9b07d99b789efb6d8dda21f1aaad636c38993
	https://git.kernel.org/stable/c/2e6871a632a99d9b9e2ce3a7847acabe99e5a26e
	https://git.kernel.org/stable/c/77d48d39e99170b528e4f2e9fc5d1d64cdedd386