From c746170d6a48b59d1233b375905f7faef6ce80bc Mon Sep 17 00:00:00 2001 From: Vincenzo Frascino Date: Tue, 22 Dec 2020 12:01:49 -0800 Subject: kasan, mm: untag page address in free_reserved_area free_reserved_area() memsets the pages belonging to a given memory area. As that memory hasn't been allocated via page_alloc, the KASAN tags that those pages have are 0x00. As the result the memset might result in a tag mismatch. Untag the address to avoid spurious faults. Link: https://lkml.kernel.org/r/ebef6425f4468d063e2f09c1b62ccbb2236b71d3.1606161801.git.andreyknvl@google.com Cc: Andrew Morton Signed-off-by: Vincenzo Frascino Signed-off-by: Andrey Konovalov Reviewed-by: Alexander Potapenko Tested-by: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Marco Elver Cc: Vasily Gorbik Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 3beeb8d722f3..1887852fb934 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7671,6 +7671,11 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char * alias for the memset(). */ direct_map_addr = page_address(page); + /* + * Perform a kasan-unchecked memset() since this memory + * has not been initialized. + */ + direct_map_addr = kasan_reset_tag(direct_map_addr); if ((unsigned int)poison <= 0xFF) memset(direct_map_addr, poison, PAGE_SIZE); -- cgit v1.2.3