From: Mel Gorman Date: Fri, 25 Jun 2021 01:40:07 +0000 (-0700) Subject: mm/page_alloc: do bulk array bounds check after checking populated elements X-Git-Tag: howlett/maple/20220722_2~2943^2~2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=b3b64ebd3822;p=users%2Fjedix%2Flinux-maple.git mm/page_alloc: do bulk array bounds check after checking populated elements Dan Carpenter reported the following The patch 0f87d9d30f21: "mm/page_alloc: add an array-based interface to the bulk page allocator" from Apr 29, 2021, leads to the following static checker warning: mm/page_alloc.c:5338 __alloc_pages_bulk() warn: potentially one past the end of array 'page_array[nr_populated]' The problem can occur if an array is passed in that is fully populated. That potentially ends up allocating a single page and storing it past the end of the array. This patch returns 0 if the array is fully populated. Link: https://lkml.kernel.org/r/20210618125102.GU30378@techsingularity.net Fixes: 0f87d9d30f21 ("mm/page_alloc: add an array-based interface to the bulk page allocator") Signed-off-by: Mel Gorman Reported-by: Dan Carpenter Cc: Jesper Dangaard Brouer Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7124bb00219d..ef2265f86b91 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5056,6 +5056,10 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, while (page_array && nr_populated < nr_pages && page_array[nr_populated]) nr_populated++; + /* Already populated array? */ + if (unlikely(page_array && nr_pages - nr_populated == 0)) + return 0; + /* Use the single page allocator for one page. */ if (nr_pages - nr_populated == 1) goto failed;