linux-cve-announce - CVE-2022-50675: arm64: mte: Avoid setting PG_mte

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025120948-CVE-2022-50675-9032@gregkh>
Date: Tue,  9 Dec 2025 10:31:00 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50675: arm64: mte: Avoid setting PG_mte_tagged if no tags cleared or restored

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

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

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

arm64: mte: Avoid setting PG_mte_tagged if no tags cleared or restored

Prior to commit 69e3b846d8a7 ("arm64: mte: Sync tags for pages where PTE
is untagged"), mte_sync_tags() was only called for pte_tagged() entries
(those mapped with PROT_MTE). Therefore mte_sync_tags() could safely use
test_and_set_bit(PG_mte_tagged, &page->flags) without inadvertently
setting PG_mte_tagged on an untagged page.

The above commit was required as guests may enable MTE without any
control at the stage 2 mapping, nor a PROT_MTE mapping in the VMM.
However, the side-effect was that any page with a PTE that looked like
swap (or migration) was getting PG_mte_tagged set automatically. A
subsequent page copy (e.g. migration) copied the tags to the destination
page even if the tags were owned by KASAN.

This issue was masked by the page_kasan_tag_reset() call introduced in
commit e5b8d9218951 ("arm64: mte: reset the page tag in page->flags").
When this commit was reverted (20794545c146), KASAN started reporting
access faults because the overriding tags in a page did not match the
original page->flags (with CONFIG_KASAN_HW_TAGS=y):

  BUG: KASAN: invalid-access in copy_page+0x10/0xd0 arch/arm64/lib/copy_page.S:26
  Read at addr f5ff000017f2e000 by task syz-executor.1/2218
  Pointer tag: [f5], memory tag: [f2]

Move the PG_mte_tagged bit setting from mte_sync_tags() to the actual
place where tags are cleared (mte_sync_page_tags()) or restored
(mte_restore_tags()).

The Linux kernel CVE team has assigned CVE-2022-50675 to this issue.

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

	Issue introduced in 5.14 with commit 69e3b846d8a753f9f279f29531ca56b0f7563ad0 and fixed in 5.15.82 with commit 918002bdbe4328c8c0164a22e8ebf2384b80dc23
	Issue introduced in 5.14 with commit 69e3b846d8a753f9f279f29531ca56b0f7563ad0 and fixed in 6.0.3 with commit 749e9fc18b1e1a3f93a9512e91bd7f93002d2821
	Issue introduced in 5.14 with commit 69e3b846d8a753f9f279f29531ca56b0f7563ad0 and fixed in 6.1 with commit a8e5e5146ad08d794c58252bab00b261045ef16d

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-2022-50675
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/arm64/kernel/mte.c
	arch/arm64/mm/mteswap.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/918002bdbe4328c8c0164a22e8ebf2384b80dc23
	https://git.kernel.org/stable/c/749e9fc18b1e1a3f93a9512e91bd7f93002d2821
	https://git.kernel.org/stable/c/a8e5e5146ad08d794c58252bab00b261045ef16d