From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v15 03/17] lib, arm64: untag user pointers in strn*_user Date: Wed, 22 May 2019 11:41:03 +0100 Message-ID: <20190522104103.r5any4us4zz7gwvg@mbp> References: <861418ff7ed7253356cb8267de5ee2d4bd84196d.1557160186.git.andreyknvl@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <861418ff7ed7253356cb8267de5ee2d4bd84196d.1557160186.git.andreyknvl@google.com> 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, Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander List-Id: linux-rdma@vger.kernel.org On Mon, May 06, 2019 at 06:30:49PM +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. > > strncpy_from_user and strnlen_user accept user addresses as arguments, and > do not go through the same path as copy_from_user and others, so here we > need to handle the case of tagged user addresses separately. > > Untag user pointers passed to these functions. > > Note, that this patch only temporarily untags the pointers to perform > validity checks, but then uses them as is to perform user memory accesses. > > Signed-off-by: Andrey Konovalov Just to keep track of where I am with the reviews while the ABI discussion continues: Reviewed-by: Catalin Marinas