LoongArch: Return NULL from huge_pte_offset() for invalid PMD

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commit bd51834d1c upstream.

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.

Cc: stable@vger.kernel.org
Acked-by: Peter Xu <peterx@redhat.com>
Co-developed-by: Hongchen Zhang <zhanghongchen@loongson.cn>
Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn>
Signed-off-by: Ming Wang <wangming01@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Ming Wang 2025-04-24 20:15:47 +08:00 • committed by Greg Kroah-Hartman

parent 93b7872d33

commit 51424fd171

1 changed files with 1 additions and 1 deletions

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arch/loongarch/mm/hugetlbpage.c

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