CVE-2024-44968 tick/broadcast: Move per CPU pointer access into the atomic section

Medium 5.5 Published Updated

A race condition in the Linux kernel's tick broadcast handling can cause a kernel bug and potential denial of service.

Exploited in the wild
Not known
Login needed
Any signed-in user
Attackable
Local or same network only
Victim action needed
Not needed
Fix
Available

What is CVE-2024-44968?

CVE-2024-44968 is a medium-severity vulnerability in Linux kernel, published on 4 Sep 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

tick/broadcast: Move per CPU pointer access into the atomic section

The recent fix for making the take over of the broadcast timer more reliable retrieves a per CPU pointer in preemptible context.

This went unnoticed as compilers hoist the access into the non-preemptible region where the pointer is actually used. But of course it's valid that the compiler keeps it at the place where the code puts it which rightfully triggers:

BUG: using smp_processor_id() in preemptible [00000000] code: caller is hotplug_cpu__broadcast_tick_pull+0x1c/0xc0

Move it to the actual usage site which is in a non-preemptible region.

Which versions are affected by CVE-2024-44968?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-44968?

Apply the vendor's patch.

Is CVE-2024-44968 being exploited?

There is no known exploitation of CVE-2024-44968 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2024-44968, DEBIAN-CVE-2024-44968, GHSA-285g-gc96-4xjh, UBUNTU-CVE-2024-44968.

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