The patch titled
Subject: mm/compaction: fix UBSAN shift-out-of-bounds warning
has been added to the -mm mm-unstable branch. Its filename is
mm-compaction-fix-ubsan-shift-out-of-bounds-warning.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-fix-ubsan-shift-out-of-bounds-warning.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liu Shixin <liushixin2@xxxxxxxxxx>
Subject: mm/compaction: fix UBSAN shift-out-of-bounds warning
Date: Thu, 23 Jan 2025 10:10:29 +0800
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@xxxxxxxxxx
Fixes: 3da0272a4c7d ("mm/compaction: correctly return failure with bogus compound_order in strict mode")
Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Cc: Mattew Wilcox <willy@xxxxxxxxxxxxx> [English fixes]
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Nanyong Sun <sunnanyong@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/compaction.c~mm-compaction-fix-ubsan-shift-out-of-bounds-warning
+++ a/mm/compaction.c
@@ -631,7 +631,8 @@ static unsigned long isolate_freepages_b
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;
_
Patches currently in -mm which might be from liushixin2@xxxxxxxxxx are
mm-page_isolation-avoid-call-folio_hstate-without-hugetlb_lock.patch
mm-compaction-fix-ubsan-shift-out-of-bounds-warning.patch
