From: David Hildenbrand <david@redhat.com> mainline inclusion from mainline-v6.13-rc4 commit faeec8e23c10bd30e8aa759a2eb3018dae00f924 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IBC4T0 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In split_large_buddy(), we might call pfn_to_page() on a PFN that might not exist. In corner cases, such as when freeing the highest pageblock in the last memory section, this could result with CONFIG_SPARSEMEM && !CONFIG_SPARSEMEM_EXTREME in __pfn_to_section() returning NULL and and __section_mem_map_addr() dereferencing that NULL pointer. Let's fix it, and avoid doing a pfn_to_page() call for the first iteration, where we already have the page. So far this was found by code inspection, but let's just CC stable as the fix is easy. Link: https://lkml.kernel.org/r/20241210093437.174413-1-david@redhat.com Fixes: fd919a85cd55 ("mm: page_isolation: prepare for hygienic freelists") Signed-off-by: David Hildenbrand <david@redhat.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Closes: https://lkml.kernel.org/r/e1a898ba-a717-4d20-9144-29df1a6c8813@suse.cz Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Yu Zhao <yuzhao@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- mm/page_alloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index eaae4051f2c7..ba8d280c3b72 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1227,13 +1227,15 @@ static void split_large_buddy(struct zone *zone, struct page *page, if (order > pageblock_order) order = pageblock_order; - while (pfn != end) { + do { int mt = get_pfnblock_migratetype(page, pfn); __free_one_page(page, pfn, zone, order, mt, fpi); pfn += 1 << order; + if (pfn == end) + break; page = pfn_to_page(pfn); - } + } while (1); } static void free_one_page(struct zone *zone, struct page *page, -- 2.43.0