Subject: CVE-2024-27009: s390/cio: fix race condition during online processing

From: Greg Kroah-Hartman <[email-masked]>

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

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

s390/cio: fix race condition during online processing

A race condition exists in ccw_device_set_online() that can cause the
online process to fail, leaving the affected device in an inconsistent
state. As a result, subsequent attempts to set that device online fail
with return code ENODEV.

The problem occurs when a path verification request arrives after
a wait for final device state completed, but before the result state
is evaluated.

Fix this by ensuring that the CCW-device lock is held between
determining final state and checking result state.

Note that since:

commit 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers")

path verification requests are much more likely to occur during boot,
resulting in an increased chance of this race condition occurring.

The Linux kernel CVE team has assigned CVE-2024-27009 to this issue.

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

	Issue introduced in 5.15 with commit 2297791c92d0 and fixed in 5.15.157 with commit 3076b3c38a70
	Issue introduced in 5.15 with commit 2297791c92d0 and fixed in 6.1.88 with commit 559f3a633339
	Issue introduced in 5.15 with commit 2297791c92d0 and fixed in 6.6.29 with commit 2df56f4ea769
	Issue introduced in 5.15 with commit 2297791c92d0 and fixed in 6.8.8 with commit a4234decd0fe
	Issue introduced in 5.15 with commit 2297791c92d0 and fixed in 6.9 with commit 2d8527f2f911

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-2024-27009
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/s390/cio/device.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/3076b3c38a704e10df5e143c213653309d532538
	https://git.kernel.org/stable/c/559f3a6333397ab6cd4a696edd65a70b6be62c6e
	https://git.kernel.org/stable/c/2df56f4ea769ff81e51bbb05699989603bde9c49
	https://git.kernel.org/stable/c/a4234decd0fe429832ca81c4637be7248b88b49e
	https://git.kernel.org/stable/c/2d8527f2f911fab84aec04df4788c0c23af3df48