linux-cve-announce - CVE-2022-49565: perf/x86/intel/lbr: Fix unchecked MSR access error on HSW

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Message-ID: <2025022605-CVE-2022-49565-e60d@gregkh>
Date: Wed, 26 Feb 2025 03:22:08 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49565: perf/x86/intel/lbr: Fix unchecked MSR access error on HSW

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

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

perf/x86/intel/lbr: Fix unchecked MSR access error on HSW

The fuzzer triggers the below trace.

[ 7763.384369] unchecked MSR access error: WRMSR to 0x689
(tried to write 0x1fffffff8101349e) at rIP: 0xffffffff810704a4
(native_write_msr+0x4/0x20)
[ 7763.397420] Call Trace:
[ 7763.399881]  <TASK>
[ 7763.401994]  intel_pmu_lbr_restore+0x9a/0x1f0
[ 7763.406363]  intel_pmu_lbr_sched_task+0x91/0x1c0
[ 7763.410992]  __perf_event_task_sched_in+0x1cd/0x240

On a machine with the LBR format LBR_FORMAT_EIP_FLAGS2, when the TSX is
disabled, a TSX quirk is required to access LBR from registers.
The lbr_from_signext_quirk_needed() is introduced to determine whether
the TSX quirk should be applied. However, the
lbr_from_signext_quirk_needed() is invoked before the
intel_pmu_lbr_init(), which parses the LBR format information. Without
the correct LBR format information, the TSX quirk never be applied.

Move the lbr_from_signext_quirk_needed() into the intel_pmu_lbr_init().
Checking x86_pmu.lbr_has_tsx in the lbr_from_signext_quirk_needed() is
not required anymore.

Both LBR_FORMAT_EIP_FLAGS2 and LBR_FORMAT_INFO have LBR_TSX flag, but
only the LBR_FORMAT_EIP_FLAGS2 requirs the quirk. Update the comments
accordingly.

The Linux kernel CVE team has assigned CVE-2022-49565 to this issue.

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

	Issue introduced in 5.17 with commit 1ac7fd8159a842b3aa51f0b46a351fa3eeb8fbf3 and fixed in 5.18.15 with commit 625bcd0685a1612225df83468c83412fc0edb3d7
	Issue introduced in 5.17 with commit 1ac7fd8159a842b3aa51f0b46a351fa3eeb8fbf3 and fixed in 5.19 with commit b0380e13502adf7dd8be4c47d622c3522aae6c63

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-2022-49565
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/events/intel/lbr.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/625bcd0685a1612225df83468c83412fc0edb3d7
	https://git.kernel.org/stable/c/b0380e13502adf7dd8be4c47d622c3522aae6c63