CVE-2021-46993
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.1 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- EPSS
- 0.24% probability · 15th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/3da3f804b82a0a382d523a21acf4cf3bb35f936dPatch
- https://git.kernel.org/stable/c/42ee47c7e3569d9a0e2cb5053c496d97d380472fPatch
- https://git.kernel.org/stable/c/687f523c134b7f0bd040ee1230f6d17990d54172Patch
- https://git.kernel.org/stable/c/6d2f8909a5fabb73fe2a63918117943986c39b6cPatch
- https://git.kernel.org/stable/c/f7347c85490b92dd144fa1fba9e1eca501656ab3Patch
- https://git.kernel.org/stable/c/3da3f804b82a0a382d523a21acf4cf3bb35f936dPatch
- https://git.kernel.org/stable/c/42ee47c7e3569d9a0e2cb5053c496d97d380472fPatch
- https://git.kernel.org/stable/c/687f523c134b7f0bd040ee1230f6d17990d54172Patch
- https://git.kernel.org/stable/c/6d2f8909a5fabb73fe2a63918117943986c39b6cPatch
- https://git.kernel.org/stable/c/f7347c85490b92dd144fa1fba9e1eca501656ab3Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.