| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-37818: LoongArch: Return NULL from huge_pte_offset() for invalid PMD |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2025-37818 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.19 with commit fa96b57c149061f71a70bd6582d995f6424fbbf4 and fixed in 6.1.136 with commit 34256805720993e37adf6127371a1265aea8376a |
| Issue introduced in 5.19 with commit fa96b57c149061f71a70bd6582d995f6424fbbf4 and fixed in 6.6.89 with commit 2ca9380b12711afe95b3589bd82b59623b3c96b3 |
| Issue introduced in 5.19 with commit fa96b57c149061f71a70bd6582d995f6424fbbf4 and fixed in 6.12.26 with commit 51424fd171cee6a33f01f7c66b8eb23ac42289d4 |
| Issue introduced in 5.19 with commit fa96b57c149061f71a70bd6582d995f6424fbbf4 and fixed in 6.14.5 with commit b49f085cd671addbda4802d6b9382513f7dd0f30 |
| Issue introduced in 5.19 with commit fa96b57c149061f71a70bd6582d995f6424fbbf4 and fixed in 6.15 with commit bd51834d1cf65a2c801295d230c220aeebf87a73 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-37818 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| arch/loongarch/mm/hugetlbpage.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| 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 |
