diff --git a/mm/page_isolation.c b/mm/page_isolation.c index e4ee998c00f3..5aaad037384e 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -419,10 +419,28 @@ static int isolate_single_pageblock(unsigned long boundary_pfn, if (PageCompound(page)) { struct page *head = compound_head(page); unsigned long head_pfn = page_to_pfn(head); - unsigned long nr_pages = compound_nr(head); + unsigned int order = compound_order(head); + unsigned long nr_pages; + + /* compound_order() is racy. Cap it at MAX_FOLIO_ORDER. */ + if (order > MAX_FOLIO_ORDER) + goto failed; + + nr_pages = 1UL << order; + + /* + * compound_head() is also racy, so the derived head_pfn + * needs additional checks to make sure it is valid. + * Otherwise, just fail the check. pfn comes from + * __first_valid_page() as a legitimate PFN, so use it to + * check head_pfn. + */ + if (head_pfn > pfn || !IS_ALIGNED(head_pfn, nr_pages) || + pfn - head_pfn >= nr_pages) + goto failed; if (head_pfn + nr_pages <= boundary_pfn || - PageHuge(page)) { + PageHuge(head)) { pfn = head_pfn + nr_pages; continue; }