CVE-2026-53123
Description
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.
Summary dbcve.org
A deadlock vulnerability in Linux kernel's MD RAID456 implementation where direct I/O can block waiting for reshape progress while holding an active_io reference. If userspace then suspends the reshape via md/suspend_lo or md/suspend_hi, the I/O cannot complete (reshape frozen) and cannot release its reference, causing suspend to hang indefinitely.
Mitigation
Apply the kernel patch that wakes raid456 reshape waiters before suspend (similar to existing dm-raid handling), allowing waiting I/O to abort and release its reference so suspend can complete.