Subject: CVE-2024-43820: dm-raid: Fix WARN_ON_ONCE check for sync_thread in raid_resume

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

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

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

dm-raid: Fix WARN_ON_ONCE check for sync_thread in raid_resume

rm-raid devices will occasionally trigger the following warning when
being resumed after a table load because DM_RECOVERY_RUNNING is set:

WARNING: CPU: 7 PID: 5660 at drivers/md/dm-raid.c:4105 raid_resume+0xee/0x100 [dm_raid]

The failing check is:
WARN_ON_ONCE(test_bit(MD_RECOVERY_RUNNING, &mddev->recovery));

This check is designed to make sure that the sync thread isn't
registered, but md_check_recovery can set MD_RECOVERY_RUNNING without
the sync_thread ever getting registered. Instead of checking if
MD_RECOVERY_RUNNING is set, check if sync_thread is non-NULL.

The Linux kernel CVE team has assigned CVE-2024-43820 to this issue.

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

	Issue introduced in 6.9 with commit 16c4770c75b1 and fixed in 6.10.3 with commit a5c15a78c0e1
	Issue introduced in 6.9 with commit 16c4770c75b1 and fixed in 6.11 with commit 3199a34bfaf7
	Issue introduced in 6.7.12 with commit af916cb66a80
	Issue introduced in 6.8.3 with commit eaa8fc9b0928

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-2024-43820
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/md/dm-raid.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/a5c15a78c0e1631b7df822b56e8b6424e4d1ca3e
	https://git.kernel.org/stable/c/3199a34bfaf7561410e0be1e33a61eba870768fc