- Vulnerability/
- CVE-2025-37818
CVE-2025-37818: LoongArch: Return NULL from huge_pte_offset() for invalid PMD
First published: Thu May 08 2025(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux kernel |
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Reference Links
- 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
Frequently Asked Questions
What is the severity of CVE-2025-37818?
CVE-2025-37818 is classified as a medium-severity vulnerability affecting the Linux kernel.
How do I fix CVE-2025-37818?
To fix CVE-2025-37818, you should upgrade to a patched version of the Linux kernel that addresses this vulnerability.
What specific systems are affected by CVE-2025-37818?
CVE-2025-37818 affects systems running the Linux kernel, particularly those using the LoongArch architecture.
What are the potential impacts of CVE-2025-37818?
The potential impacts of CVE-2025-37818 include instability or incorrect memory management leading to application failures.
Is CVE-2025-37818 publicly known?
Yes, CVE-2025-37818 is a publicly disclosed vulnerability and detailed information is available in security advisories.
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