On Fri, Nov 13, 2020 at 11:17 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> > > 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. > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> > --- > Change-Id: If12b4944383575b8bbd7d971decbd7f04be6748b > --- > mm/page_alloc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 855627e52f81..4a69fef13ac7 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7653,6 +7653,11 @@ 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); > > -- > 2.29.2.299.gdc1121823c-goog > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
