From acb35b177c71d3d39b9a3b9ea213d926235066e3 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Sat, 23 Jan 2021 21:01:43 -0800 Subject: kasan, mm: fix resetting page_alloc tags for HW_TAGS A previous commit added resetting KASAN page tags to kernel_init_free_pages() to avoid false-positives due to accesses to metadata with the hardware tag-based mode. That commit did reset page tags before the metadata access, but didn't restore them after. As the result, KASAN fails to detect bad accesses to page_alloc allocations on some configurations. Fix this by recovering the tag after the metadata access. Link: https://lkml.kernel.org/r/02b5bcd692e912c27d484030f666b350ad7e4ae4.1611074450.git.andreyknvl@google.com Fixes: aa1ef4d7b3f6 ("kasan, mm: reset tags when accessing metadata") Signed-off-by: Andrey Konovalov Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Marco Elver Cc: Catalin Marinas Cc: Will Deacon Cc: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Peter Collingbourne Cc: Evgenii Stepanov Cc: Branislav Rankov Cc: Kevin Brodsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 85ecaa6d0d06..783913e41f65 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1207,8 +1207,10 @@ static void kernel_init_free_pages(struct page *page, int numpages) /* s390's use of memset() could override KASAN redzones. */ kasan_disable_current(); for (i = 0; i < numpages; i++) { + u8 tag = page_kasan_tag(page + i); page_kasan_tag_reset(page + i); clear_highpage(page + i); + page_kasan_tag_set(page + i, tag); } kasan_enable_current(); } -- cgit v1.2.3