From 26d6c6ff969eadb63d0b56cd9ccf8a50e8ab769d Mon Sep 17 00:00:00 2001 From: Liu Shixin Date: Thu, 23 Jan 2025 10:10:29 +0800 Subject: [PATCH] mm/compaction: fix UBSAN shift-out-of-bounds warning BugLink: https://bugs.launchpad.net/bugs/2114239 commit d1366e74342e75555af2648a2964deb2d5c92200 upstream. syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order) in isolate_freepages_block(). The bogus compound_order can be any value because it is union with flags. Add back the MAX_PAGE_ORDER check to fix the warning. Link: https://lkml.kernel.org/r/20250123021029.2826736-1-liushixin2@huawei.com Fixes: 3da0272a4c7d ("mm/compaction: correctly return failure with bogus compound_order in strict mode") Signed-off-by: Liu Shixin Reviewed-by: Kemeng Shi Acked-by: David Hildenbrand Reviewed-by: Oscar Salvador Cc: Baolin Wang Cc: David Hildenbrand Cc: Kemeng Shi Cc: Matthew Wilcox Cc: Mel Gorman Cc: Nanyong Sun Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman Signed-off-by: Noah Wager Signed-off-by: Mehmet Basaran --- mm/compaction.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index b961db601df4..47f1a25eeae0 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -625,7 +625,8 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, if (PageCompound(page)) { const unsigned int order = compound_order(page); - if (blockpfn + (1UL << order) <= end_pfn) { + if ((order <= MAX_PAGE_ORDER) && + (blockpfn + (1UL << order) <= end_pfn)) { blockpfn += (1UL << order) - 1; page += (1UL << order) - 1; nr_scanned += (1UL << order) - 1;