CVE-2026-74373: md/raid1,raid10: fix bio accounting for split md cloned bios

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

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

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

md/raid1,raid10: fix bio accounting for split md cloned bios

Use md_cloned_bio() to control bio accounting instead of relying
on r1bio_existed in raid1 or the io_accounting flag in raid10.

The previous logic does not reliably reflect whether a bio is an
md cloned bio. When a failed bio is split and resubmitted via
bio_submit_split_bioset() on the error path, this can lead to either
double accounting for md cloned bios, or missing accounting for bios
returned from bio_submit_split_bioset()

Fix this by using md_cloned_bio() to detect md cloned bios and
skip accounting accordingly.

The Linux kernel CVE team has assigned CVE-2026-74373 to this issue.


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

	Issue introduced in 6.6 with commit bb2a9acefaf9ce5bbc1e70f407e34599233d0243 and fixed in 7.1.5 with commit bb8d7ea74206b419aa05d7773a15a923b668c9f0
	Issue introduced in 6.6 with commit bb2a9acefaf9ce5bbc1e70f407e34599233d0243 and fixed in 7.2-rc1 with commit ba976e3501111d11c550848b3b7341a73035f582

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-2026-74373
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/raid1.c
	drivers/md/raid10.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/bb8d7ea74206b419aa05d7773a15a923b668c9f0
	https://git.kernel.org/stable/c/ba976e3501111d11c550848b3b7341a73035f582