From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Date: Thu, 16 Jun 2016 08:05:38 +0200 From: Heiko Carstens References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Message-Id: <20160616060538.GA3923@osiris> Subject: [kernel-hardening] Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) To: Andy Lutomirski Cc: "linux-kernel@vger.kernel.org" , x86@kernel.org, Borislav Petkov , Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf List-ID: On Wed, Jun 15, 2016 at 05:28:22PM -0700, Andy Lutomirski wrote: > Since the dawn of time, a kernel stack overflow has been a real PITA > to debug, has caused nondeterministic crashes some time after the > actual overflow, and has generally been easy to exploit for root. > > With this series, arches can enable HAVE_ARCH_VMAP_STACK. Arches > that enable it (just x86 for now) get virtually mapped stacks with > guard pages. This causes reliable faults when the stack overflows. > > If the arch implements it well, we get a nice OOPS on stack overflow > (as opposed to panicing directly or otherwise exploding badly). On > x86, the OOPS is nice, has a usable call trace, and the overflowing > task is killed cleanly. Do you have numbers which reflect the performance impact of this change?