linux-cve-announce - CVE-2022-49172: parisc: Fix non-access data TLB cache flush faults

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Message-ID: <2025022612-CVE-2022-49172-3fe3@gregkh>
Date: Wed, 26 Feb 2025 02:56:17 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49172: parisc: Fix non-access data TLB cache flush faults

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

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

parisc: Fix non-access data TLB cache flush faults

When a page is not present, we get non-access data TLB faults from
the fdc and fic instructions in flush_user_dcache_range_asm and
flush_user_icache_range_asm. When these occur, the cache line is
not invalidated and potentially we get memory corruption. The
problem was hidden by the nullification of the flush instructions.

These faults also affect performance. With pa8800/pa8900 processors,
there will be 32 faults per 4 KB page since the cache line is 128
bytes.  There will be more faults with earlier processors.

The problem is fixed by using flush_cache_pages(). It does the flush
using a tmp alias mapping.

The flush_cache_pages() call in flush_cache_range() flushed too
large a range.

V2: Remove unnecessary preempt_disable() and preempt_enable() calls.

The Linux kernel CVE team has assigned CVE-2022-49172 to this issue.

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

	Fixed in 5.16.19 with commit b3d6adb3a49d82e4e557c5fc16f50c9ff731da5d
	Fixed in 5.17.2 with commit ddca4b82027e2a66333dd40fab21a4beff435c7e
	Fixed in 5.18 with commit f839e5f1cef36ce268950c387129b1bfefdaebc9

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-2022-49172
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/parisc/kernel/cache.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/b3d6adb3a49d82e4e557c5fc16f50c9ff731da5d
	https://git.kernel.org/stable/c/ddca4b82027e2a66333dd40fab21a4beff435c7e
	https://git.kernel.org/stable/c/f839e5f1cef36ce268950c387129b1bfefdaebc9