CVE-2021-46993 Information

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 [019] hence leading to an out of bound memory access.

Clamp the bucket id to fix the issue.

Reference

https://git.kernel.org/stable/c/687f523c134b7f0bd040ee1230f6d17990d54172 https://git.kernel.org/stable/c/f7347c85490b92dd144fa1fba9e1eca501656ab3 https://git.kernel.org/stable/c/3da3f804b82a0a382d523a21acf4cf3bb35f936d https://git.kernel.org/stable/c/42ee47c7e3569d9a0e2cb5053c496d97d380472f https://git.kernel.org/stable/c/6d2f8909a5fabb73fe2a63918117943986c39b6c