Medium [CVE-2026-53123] wake raid456 reshape waiters before suspend

In the Linux kernel, the following vulnerability has been resolved: md: wake raid456 reshape waiters before suspend During raid456 reshape, direct IO across the reshape position can sleep in raid5_make_request() waiting for reshape progress while still holding an active_io reference.

If userspace then freezes reshape and writes md/suspend_lo or md/suspend_hi, mddev_suspend() kills active_io and waits for all in-flight IO to drain.

This can deadlock: the IO needs reshape progress to continue, but the reshape thread is already frozen, so the active_io reference is never dropped and suspend never completes. raid5_prepare_suspend() already wakes wait_for_reshape for dm-raid.

Do the same for normal md suspend when reshape is already interrupted, so waiting raid456 IO can abort, drop its reference, and let suspend finish. The mdadm test tests/25raid456-reshape-deadlock reproduces the hang.

A flaw was found in the Linux kernel's Multiple Device (MD) driver, specifically within the raid456 reshape functionality. A local user could trigger a deadlock by freezing the reshape process and writing to the md/suspend_lo or md/suspend_hi files while direct I/O operations are in progress.

This condition prevents the system from completing the suspend operation, leading to a Denial of Service (DoS). Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).