CVE-2024-42245: In the Linux kernel, the following vulnerability has been resolved: Revert "sched/fair: Make sure to try to detach at least one movable task" This r...

Description

In the Linux kernel, the following vulnerability has been resolved: Revert "sched/fair: Make sure to try to detach at least one movable task" This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06. b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if all tasks examined to that point were pinned. The goal of the patch was to make it more likely to be able to detach a task buried in a long list of pinned tasks. However, this has the unfortunate side effect of creating an O(n) iteration in detach_tasks(), as we now must fully iterate every task on a cpu if all or most are pinned. Since this load balance code is done with rq lock held, and often in softirq context, it is very easy to trigger hard lockups. We observed such hard lockups with a user who affined O(10k) threads to a single cpu. When I discussed this with Vincent he initially suggested that we keep the limit on the number of tasks to detach, but increase the number of tasks we can search. However, after some back and forth on the mailing list, he recommended we instead revert the original patch, as it seems likely no one was actually getting hit by the original issue.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.17%

6.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-667

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 6.1, < 6.1.100
Linux	Linux Kernel	>= 6.2, < 6.6.41
Linux	Linux Kernel	>= 6.7, < 6.9.10

References

Timeline

Published: Aug 7, 2024
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2024-42245?

In the Linux kernel, the following vulnerability has been resolved: Revert "sched/fair: Make sure to try to detach at least one movable task" This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06. b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if all tasks examined to that point were pinned. The goal of the patch was to make it more likely to be able to detach a task buried in a long list of pinned tasks. However, this has the unfortunate side effect of creating an O(n) iteration in detach_tasks(), as we now must fully iterate every task on a cpu if all or most are pinned. Since this load balance code is done with rq lock held, and often in softirq context, it is very easy to trigger hard lockups. We observed such hard lockups with a user who affined O(10k) threads to a single cpu. When I discussed this with Vincent he initially suggested that we keep the limit on the number of tasks to detach, but increase the number of tasks we can search. However, after some back and forth on the mailing list, he recommended we instead revert the original patch, as it seems likely no one was actually getting hit by the original issue.

How severe is CVE-2024-42245?

CVE-2024-42245 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2024-42245?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.