CVE-2025-37818 Information

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.

Reference

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