From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.deacon@arm.com (Will Deacon)
Date: Thu, 18 Feb 2016 18:03:54 +0000
Subject: [PATCH] arm64: kasan: clear stale stack poison
In-Reply-To: <20160218175447.GD2538@e104818-lin.cambridge.arm.com>
References: <1455816458-19485-1-git-send-email-mark.rutland@arm.com>
 <20160218175447.GD2538@e104818-lin.cambridge.arm.com>
Message-ID: <20160218180353.GG16883@arm.com>
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On Thu, Feb 18, 2016 at 05:54:47PM +0000, Catalin Marinas wrote:
> On Thu, Feb 18, 2016 at 05:27:38PM +0000, Mark Rutland wrote:
> > @@ -145,6 +146,7 @@ ENTRY(cpu_resume_mmu)
> >  ENDPROC(cpu_resume_mmu)
> >  	.popsection
> >  cpu_resume_after_mmu:
> > +	kasan_unpoison_stack 96
> 
> I don't think the 96 here is needed since we populate the stack in
> assembly (__cpu_suspend_enter) and unwind it again still in assembly
> (cpu_resume_after_mmu), so no KASAN shadow writes/reads.
> 
> Otherwise the patch looks fine.

I'd much rather it was written in C -- is there a reason we can't do
that if we use a separate compilation unit where the compiler will
honour the fno-sanitize flag?

Will

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Date: Thu, 18 Feb 2016 18:03:54 +0000
From: Will Deacon <will.deacon@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>, mingo@kernel.org,
        Andrey Ryabinin <aryabinin@virtuozzo.com>, akpm@linux-foundation.org,
        hpa@linux.intel.com, tglx@linutronix.de
Subject: Re: [PATCH] arm64: kasan: clear stale stack poison
Message-ID: <20160218180353.GG16883@arm.com>
References: <1455816458-19485-1-git-send-email-mark.rutland@arm.com>
 <20160218175447.GD2538@e104818-lin.cambridge.arm.com>
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On Thu, Feb 18, 2016 at 05:54:47PM +0000, Catalin Marinas wrote:
> On Thu, Feb 18, 2016 at 05:27:38PM +0000, Mark Rutland wrote:
> > @@ -145,6 +146,7 @@ ENTRY(cpu_resume_mmu)
> >  ENDPROC(cpu_resume_mmu)
> >  	.popsection
> >  cpu_resume_after_mmu:
> > +	kasan_unpoison_stack 96
> 
> I don't think the 96 here is needed since we populate the stack in
> assembly (__cpu_suspend_enter) and unwind it again still in assembly
> (cpu_resume_after_mmu), so no KASAN shadow writes/reads.
> 
> Otherwise the patch looks fine.

I'd much rather it was written in C -- is there a reason we can't do
that if we use a separate compilation unit where the compiler will
honour the fno-sanitize flag?

Will