CVE-2025-71225: md: suspend array while updating raid_disks via sysfs

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-18 · updated 2026-10-21
Weakness: CWE-367

Description

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.

Affected products

Linux kernel: from 3.4.59 before 3.5; from 3.9.7 before 3.10; from 3.10.1 before 6.12.70; from 6.13 before 6.18.10; 3.10, 3.10-rc6, 3.10-rc7, 6.19-rc1, 6.19-rc2, 6.19-rc3 — fixed in 3.10, 3.5, 6.12.70, 6.18.10

How to fix

Upgrade to a fixed version: Linux kernel 3.10, 3.5, 6.12.70, 6.18.10. Check the vendor advisory for mitigations.

References

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