On Fri, Nov 13, 2020 at 11:15:54PM +0100, Andrey Konovalov wrote: > From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> > > The hardware tag-based KASAN for compatibility with the other modes > stores the tag associated to a page in page->flags. > Due to this the kernel faults on access when it allocates a page with an > initial tag and the user changes the tags. > > Reset the tag associated by the kernel to a page in all the meaningful > places to prevent kernel faults on access. > > Note: An alternative to this approach could be to modify page_to_virt(). > This though could end up being racy, in fact if a CPU checks the > PG_mte_tagged bit and decides that the page is not tagged but another > CPU maps the same with PROT_MTE and becomes tagged the subsequent kernel > access would fail. > > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
