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Date: Wed, 7 Nov 2018 18:26:27 +0000
From: Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v10 12/22] kasan, arm64: fix up fault handling logic
Message-ID: <20181107182626.GD255021@arrakis.emea.arm.com>
References: <cover.1541525354.git.andreyknvl@google.com>
 <4891a504adf61c0daf1e83642b6f7519328dfd5f.1541525354.git.andreyknvl@google.com>
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To: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>, Alexander Potapenko <glider@google.com>, Dmitry Vyukov <dvyukov@google.com>, Will Deacon <will.deacon@arm.com>, Christoph Lameter <cl@linux.com>, Andrew Morton <akpm@linux-foundation.org>, Mark Rutland <mark.rutland@arm.com>, Nick Desaulniers <ndesaulniers@google.com>, Marc Zyngier <marc.zyngier@arm.com>, Dave Martin <dave.martin@arm.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, "Eric W . Biederman" <ebiederm@xmission.com>, Ingo Molnar <mingo@kernel.org>, Paul Lawrence <paullawrence@google.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Arnd Bergmann <arnd@arndb.de>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Kate Stewart <kstewart@linuxfoundation.org>, Mike Rapoport <rppt@linux.vnet.ibm.com>, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, Vishwath Mohan <vishwath@google.com>, Chintan Pandya <cpandya@codeaurora.org>, Jacob Bramley <Jacob.Bramley@arm.com>, Jann Horn <jannh@google.com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Lee Smith <Lee.Smith@arm.com>, Kostya Serebryany <kcc@google.com>, Mark Brand <markbrand@google.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Evgeniy Stepanov <eugenis@google.com>

On Tue, Nov 06, 2018 at 06:30:27PM +0100, Andrey Konovalov wrote:
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 7d9571f4ae3d..d9a84d6f3343 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -32,6 +32,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/preempt.h>
>  #include <linux/hugetlb.h>
> +#include <linux/kasan.h>
>  
>  #include <asm/bug.h>
>  #include <asm/cmpxchg.h>
> @@ -141,6 +142,8 @@ void show_pte(unsigned long addr)
>  	pgd_t *pgdp;
>  	pgd_t pgd;
>  
> +	addr = (unsigned long)kasan_reset_tag((void *)addr);
> +
>  	if (addr < TASK_SIZE) {
>  		/* TTBR0 */
>  		mm = current->active_mm;

I think we should clear the tag earlier on in the fault handling code,
before reaching show_pte().

-- 
Catalin