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Review reviewHigh

CVE-2021-46993

Linux Linux, linux kernel

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...

CVSS
7.1
EPSS
-
- percentile
CISA KEV
Not listed
Published
2024.02.28
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.1

Vulnerability overview

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...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= 69842cba9ace84849bb9b8edcdf2cefccd97901c < 687f523c134b7f0bd040ee1230f6d17990d54172, >= 69842cba9ace84849bb9b8edcdf2cefccd97901c < f7347c85490b92dd144fa1fba9e1eca501656ab3, >= 69842cba9ace84849bb9b8edcdf2cefccd97901c < 3da3f804b82a0a382d523a21acf4cf3bb35f936d, >= 69842cba9ace84849bb9b8edcdf2cefccd97901c < 42ee47c7e3569d9a0e2cb5053c496d97d380472f, >= 69842cba9ace84849bb9b8edcdf2cefccd97901c < 6d2f8909a5fabb73fe2a63918117943986c39b6c, >= 5.3, >= 5.3 < 5.4.120, >= 5.5 < 5.10.38, >= 5.11 < 5.11.22, >= 5.12 < 5.12.5
Fixed versions
5.4.120, 5.10.38, 5.11.22, 5.12.5

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
CWE
CWE-125