Vulnerability · Published May 8, 2025 · Assigned by Linux
CVE-2025-37818LoongArch: Return NULL from huge_pte_offset() for invalid PMD
Medium 5.5
In plain English
A medium-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | linux | 6.1.137-1 | DEBIAN-CVE-2025-37818 |
| Debian:13 | linux | 6.12.27-1 | DEBIAN-CVE-2025-37818 |
| Debian:14 | linux | 6.12.27-1 | DEBIAN-CVE-2025-37818 |
| Ubuntu:24.04:LTS | linux-gcp-6.14 | 6.14.0-1011.11~24.04.1 | UBUNTU-CVE-2025-37818 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | fa96b57c149061f71a70bd6582d995f6424fbbf4 – before 34256805720993e37adf6127371a1265aea8376afa96b57c149061f71a70bd6582d995f6424fbbf4 – before 2ca9380b12711afe95b3589bd82b59623b3c96b3fa96b57c149061f71a70bd6582d995f6424fbbf4 – before 51424fd171cee6a33f01f7c66b8eb23ac42289d4fa96b57c149061f71a70bd6582d995f6424fbbf4 – before b49f085cd671addbda4802d6b9382513f7dd0f30fa96b57c149061f71a70bd6582d995f6424fbbf4 – before bd51834d1cf65a2c801295d230c220aeebf87a73 |
| Linux | Linux | 5.19 |
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
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html