cve/published/2022/CVE-2022-49223.mbox

From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2022-49223: cxl/port: Hold port reference until decoder release

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

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

cxl/port: Hold port reference until decoder release

KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in
cxl_decoder_release() where it goes to reference its parent, a cxl_port,
to free its id back to port->decoder_ida.

 BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core]
 Read of size 8 at addr ffff888119270908 by task kworker/35:2/379

 CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G           OE     5.17.0-rc2+ #198
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 Workqueue: events kobject_delayed_cleanup
 Call Trace:
  <TASK>
  dump_stack_lvl+0x59/0x73
  print_address_description.constprop.0+0x1f/0x150
  ? to_cxl_port+0x18/0x90 [cxl_core]
  kasan_report.cold+0x83/0xdf
  ? to_cxl_port+0x18/0x90 [cxl_core]
  to_cxl_port+0x18/0x90 [cxl_core]
  cxl_decoder_release+0x2a/0x60 [cxl_core]
  device_release+0x5f/0x100
  kobject_cleanup+0x80/0x1c0

The device core only guarantees parent lifetime until all children are
unregistered. If a child needs a parent to complete its ->release()
callback that child needs to hold a reference to extend the lifetime of
the parent.

The Linux kernel CVE team has assigned CVE-2022-49223 to this issue.


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

	Issue introduced in 5.14 with commit 40ba17afdfabb01688c61565dbe02a916241bc05 and fixed in 5.15.54 with commit 518bb96367123062b48b0a9842f2864249b565f6
	Issue introduced in 5.14 with commit 40ba17afdfabb01688c61565dbe02a916241bc05 and fixed in 5.16.19 with commit b0022ca445d5fc4d0c89d15dcd0f855977b22c1d
	Issue introduced in 5.14 with commit 40ba17afdfabb01688c61565dbe02a916241bc05 and fixed in 5.17.2 with commit 49f2dab77a5e1354f5da6ccdc9346a8212697be2
	Issue introduced in 5.14 with commit 40ba17afdfabb01688c61565dbe02a916241bc05 and fixed in 5.18 with commit 74be98774dfbc5b8b795db726bd772e735d2edd4

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-2022-49223
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/cxl/core/port.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/518bb96367123062b48b0a9842f2864249b565f6
	https://git.kernel.org/stable/c/b0022ca445d5fc4d0c89d15dcd0f855977b22c1d
	https://git.kernel.org/stable/c/49f2dab77a5e1354f5da6ccdc9346a8212697be2
	https://git.kernel.org/stable/c/74be98774dfbc5b8b795db726bd772e735d2edd4