Date: Mon, 2 Jul 2018 10:59:32 +0100 From: Will Deacon <will.deacon@....com> To: Kees Cook <keescook@...omium.org> Cc: Laura Abbott <labbott@...hat.com>, Mark Rutland <mark.rutland@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, LKML <linux-kernel@...r.kernel.org>, linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, Alexander Popov <alex.popov@...ux.com>, catalin.marinas@....com Subject: Re: [PATCH] arm64: Clear the stack Hi Kees, On Fri, Jun 29, 2018 at 01:25:20PM -0700, Kees Cook wrote: > On Fri, Jun 29, 2018 at 1:22 PM, Laura Abbott <labbott@...hat.com> wrote: > > On 06/29/2018 01:19 PM, Kees Cook wrote: > >> > >> On Fri, Jun 29, 2018 at 12:05 PM, Laura Abbott <labbott@...hat.com> wrote: > >>> > >>> Implementation of stackleak based heavily on the x86 version > >>> > >>> Signed-off-by: Laura Abbott <labbott@...hat.com> > >>> [...] > >>> +#define current_top_of_stack() (task_stack_page(current) + THREAD_SIZE) > >>> +#define on_thread_stack() (on_task_stack(current, > >>> current_stack_pointer)) > >> > >> > >> nit on types here. I get some warnings: > >> > >> kernel/stackleak.c:55:12: warning: assignment makes integer from > >> pointer without a cast [-Wint-conversion] > >> boundary = current_top_of_stack(); > >> ^ > >> kernel/stackleak.c:65:24: warning: assignment makes integer from > >> pointer without a cast [-Wint-conversion] > >> current->lowest_stack = current_top_of_stack() - THREAD_SIZE / 64; > >> ^ > >> > >> So I think this needs to be: > >> > >> +#define current_top_of_stack() ((unsigned long)task_stack_page(current) + > >> \ > >> + THREAD_SIZE) > >> > > > > Argh, missed that in an amend, can fix for next version if there > > are no other objections to this approach. > > No worries! I've made the change locally and will push this out to > -next unless there are objections? I'm a bit wary of conflicts in entry.S, since it's likely that we're going to have a lot going on in there for 4.19. Could I take this via arm64 instead, please, or are there dependencies on other parts of your tree? Will
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