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.

Classification

CVE ID: CVE-2025-37818

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 4.72% (scored less or equal to compared to others)

EPSS Date: 2025-06-06 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-37818
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

Timeline