CVE-2026-89997: dm: fix resume-vs-remove race
In the Linux kernel, the following vulnerability has been resolved:
dm: fix resume-vs-remove race
If the user issues the resume ioctl and the remove ioctl at the same time, it may be possible that the device is resumed after it is suspended in dmdestroy. The result is that the table is destroyed without calling the postsuspend method.
Dm targets expect that they may be removed only after the postsuspend method method was called. If we break this expectation, it can cause misbehavior in various targets. For example - in the dm-integrity target, the reboot notifier is not unregistered, leading to use-after-free.
Fix this bug by refusing to resume if the device is being destroyed.
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Fix the dm resume-vs-remove race by refusing to resume (on resume ioctl) if the device is in the middle of being destroyed, so that __dm_destroy does not destroy the table without calling postsuspend.
Linux device-mapper (dm) resume behavior during device destruction = refuse/resume blocked when device is being destroyed - Compensating control
As a mitigation until the kernel fix is applied, avoid issuing the dm remove ioctl while a dm resume ioctl could be concurrently processed for the same device (serialize remove/resume operations) to prevent the resume-after-suspend / use-after-free conditions described.
Event History
Frequently Asked Questions
What condition is required to trigger the race?
The resume ioctl and remove ioctl must be issued concurrently for the same device. The race can allow a device to resume after destruction has begun.
Which device-mapper targets may be affected?
The issue can cause misbehavior in targets that rely on postsuspend being called before removal. The description specifically identifies dm-integrity, where a reboot notifier may remain registered and lead to use-after-free.
What is the practical effect of the dm-integrity failure?
If the expected postsuspend cleanup is skipped, dm-integrity may fail to unregister its reboot notifier. That stale notifier can result in a use-after-free.
What behavior does the fix introduce?
The fix refuses resume requests when the device is being destroyed. This prevents a resume from racing with removal after suspension has started.