Date: Mon, 14 May 2018 15:07:15 +0100 From: Mark Rutland <mark.rutland@....com> To: Alexander Popov <alex.popov@...ux.com> Cc: Andy Lutomirski <luto@...nel.org>, Laura Abbott <labbott@...hat.com>, Kees Cook <keescook@...omium.org>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, kernel-hardening@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/2] arm64: Clear the stack On Mon, May 14, 2018 at 04:53:12PM +0300, Alexander Popov wrote: > On 14.05.2018 13:06, Mark Rutland wrote: > > I think it is reasonable to panic() here even with CONFIG_VMAP_STACK > > selected. > > It's too tough for CONFIG_VMAP_STACK on x86 - the system can proceed to live. > Anyway, the check_alloca() code will not be shared between x86 and arm64, I've > described the reasons in this thread. So I can have BUG() for CONFIG_VMAP_STACK > on x86 and Laura can consistently use panic() on arm64. If we need arch-specific implementations anyway, then that's fine by me. > >> So we should not do it in check_alloca() as well, just use BUG() and > >> hope for the best. > > > > Regardless of whether we BUG() or panic(), we're hoping for the best. > > > > Consistently using panic() here will keep things simpler, so any failure > > reported will be easier to reason about, and easier to debug. > > Let me keep BUG() for !CONFIG_SCHED_STACK_END_CHECK. I beware of using panic() > by default, let distro/user decide this. I remember very well how I was shouted > at, when this one was merged: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce6fa91b93630396ca220c33dd38ffc62686d499 Sure; my comments needn't hold up your patches. Thanks, Mark.
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