mm/page_alloc: init local variable buddy_pfn

The local variable buddy_pfn could be passed to buddy_merge_likely()
without initialization if the passed in order is MAX_ORDER - 1.  This
looks buggy but buddy_pfn won't be used in this case as there's a order >=
MAX_ORDER - 2 check.  Init buddy_pfn to 0 anyway to avoid possible future
misuse.

Link: https://lkml.kernel.org/r/20220916072257.9639-14-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3216477d9ba653c65e38db08a4917a25f1e797ad..4dc2fe575fc8dfb8e3996ac066a8448bc18dacc0 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1113,7 +1113,7 @@ static inline void __free_one_page(struct page *page,
                int migratetype, fpi_t fpi_flags)
 {
        struct capture_control *capc = task_capc(zone);
-       unsigned long buddy_pfn;
+       unsigned long buddy_pfn = 0;
        unsigned long combined_pfn;
        struct page *buddy;
        bool to_tail;