CVE-2021-46993 sched: Fix out-of-bound access in uclamp
An out-of-bounds memory access in the Linux kernel scheduler allows attackers to potentially execute code or cause a system crash.
- 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-2021-46993?
CVE-2021-46993 is a high-severity memory corruption vulnerability in Linux kernel, published on 28 Feb 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:
sched: Fix out-of-bound access in uclamp
Util-clamp places tasks in different buckets based on their clamp values for performance reasons. However, the size of buckets is currently computed using a rounding division, which can lead to an off-by-one error in some configurations.
For instance, with 20 buckets, the bucket size will be 1024/20=51. A task with a clamp of 1024 will be mapped to bucket id 1024/51=20. Sadly, correct indexes are in range [0,19], hence leading to an out of bound memory access.
Clamp the bucket id to fix the issue.
Weakness: CWE-125
Which versions are affected by CVE-2021-46993?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-46993?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2021-46993 being exploited?
There is no known exploitation of CVE-2021-46993 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-46993, GHSA-gwvc-g8fg-56vx, UBUNTU-CVE-2021-46993.