CVE-2026-74372: raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path

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

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

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

raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path

In raid1_write_request(), each per-mirror loop iteration begins by
incrementing rdev->nr_pending. If a REQ_ATOMIC write encounters a
badblock within the requested range, the code jumps to err_handle
without dropping the reference taken for the current mirror.

err_handle's cleanup loop will only decrements for k < i and
r1_bio->bios[k] is non-NULL. The current slot is therefore skipped,
leaving its nr_pending reference leaked permanently. The reference
prevents the rdev from ever being removed, since raid1_remove_conf()
refuses to remove an rdev with nr_pending > 0.

Fix this by calling rdev_dec_pending() before jumping to err_handle.

The Linux kernel CVE team has assigned CVE-2026-74372 to this issue.


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

	Issue introduced in 6.13 with commit f2a38abf5f1c5aeb3be8e9f4d3d815c867fff7ca and fixed in 6.18.40 with commit 5ac9e793ba2583d72740d929e7858a6c82e22ed5
	Issue introduced in 6.13 with commit f2a38abf5f1c5aeb3be8e9f4d3d815c867fff7ca and fixed in 7.1.5 with commit 731485617bf862f1289c3f40ed1f800d0475826f
	Issue introduced in 6.13 with commit f2a38abf5f1c5aeb3be8e9f4d3d815c867fff7ca and fixed in 7.2-rc1 with commit 909d9dc3b5730c8ed7b764c68bc788342df2a07b

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-2026-74372
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


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/5ac9e793ba2583d72740d929e7858a6c82e22ed5
	https://git.kernel.org/stable/c/731485617bf862f1289c3f40ed1f800d0475826f
	https://git.kernel.org/stable/c/909d9dc3b5730c8ed7b764c68bc788342df2a07b