From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: [PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames Date: Fri, 7 Jun 2019 21:00:26 -0700 Message-ID: <201906072059.69C8284A0E@keescook> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Andrey Konovalov Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Catalin Marinas , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander List-Id: linux-rdma@vger.kernel.org On Mon, Jun 03, 2019 at 06:55:09PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > get_vaddr_frames uses provided user pointers for vma lookups, which can > only by done with untagged pointers. Instead of locating and changing > all callers of this function, perform untagging in it. > > Signed-off-by: Andrey Konovalov Reviewed-by: Kees Cook -Kees > --- > mm/frame_vector.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > index c64dca6e27c2..c431ca81dad5 100644 > --- a/mm/frame_vector.c > +++ b/mm/frame_vector.c > @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) > nr_frames = vec->nr_allocated; > > + start = untagged_addr(start); > + > down_read(&mm->mmap_sem); > locked = 1; > vma = find_vma_intersection(mm, start, start + 1); > -- > 2.22.0.rc1.311.g5d7573a151-goog > -- Kees Cook