Bug 2440627 (CVE-2025-71225)

Summary:	CVE-2025-71225 kernel: md: suspend array while updating raid_disks via sysfs
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	---
Doc Text:	A race condition flaw was found in the Linux kernel's MD RAID1 driver. When updating the raid_disks count via sysfs during concurrent I/O errors, the freeze_array() function may return before all queued r1bio structures are released. This can cause free_r1bio() to access memory out of bounds and potentially corrupt the memory pool when r1bios allocated with the old raid_disks value are freed to the resized mempool.	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-02-18 15:02:27 UTC

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

md: suspend array while updating raid_disks via sysfs

In raid1_reshape(), freeze_array() is called before modifying the r1bio
memory pool (conf->r1bio_pool) and conf->raid_disks, and
unfreeze_array() is called after the update is completed.

However, freeze_array() only waits until nr_sync_pending and
(nr_pending - nr_queued) of all buckets reaches zero. When an I/O error
occurs, nr_queued is increased and the corresponding r1bio is queued to
either retry_list or bio_end_io_list. As a result, freeze_array() may
unblock before these r1bios are released.

This can lead to a situation where conf->raid_disks and the mempool have
already been updated while queued r1bios, allocated with the old
raid_disks value, are later released. Consequently, free_r1bio() may
access memory out of bounds in put_all_bios() and release r1bios of the
wrong size to the new mempool, potentially causing issues with the
mempool as well.

Since only normal I/O might increase nr_queued while an I/O error occurs,
suspending the array avoids this issue.

Note: Updating raid_disks via ioctl SET_ARRAY_INFO already suspends
the array. Therefore, we suspend the array when updating raid_disks
via sysfs to avoid this issue too.

Comment 1 Alexander B 2026-02-18 17:15:53 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026021859-CVE-2025-71225-44de@gregkh/T