From mboxrd@z Thu Jan  1 00:00:00 1970
From: Khalid Aziz <khalid.aziz@oracle.com>
Subject: Re: [PATCH v17 06/15] mm, arm64: untag user pointers in
 get_vaddr_frames
Date: Wed, 19 Jun 2019 10:48:38 -0600
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To: Andrey Konovalov <andreyknvl@google.com>, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>, Szabolcs Nagy <Szabolcs.Nagy@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Kostya Serebryany <kcc@google.com>, Felix Kuehling <Felix.Kuehling@amd.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Jacob Bramley <Jacob.Bramley@arm.com>, Leon Romanovsky <leon@kernel.org>, Christoph Hellwig <hch@infradead.org>, Jason Gunthorpe <jgg@ziepe.ca>, Dave Martin <Dave.Martin@arm.com>, Evgeniy Stepanov <eugenis@google.com>, Kevin Brodsky <kevin.brodsky@arm.com>, Kees Cook <keescook@chromium.org>, Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>, Alex Williamson <alex.williamson@redhat.com>, Mauro Carvalho Chehab <mchehab@kernel.org>, Dmitry Vyukov <dvyukov@google.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Yishai Hadas <yishaih@mellanox.com>J
List-Id: linux-rdma@vger.kernel.org

On 6/12/19 5:43 AM, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> get_vaddr_frames uses provided user pointers for vma lookups, which can
> only by done with untagged pointers. Instead of locating and changing
> all callers of this function, perform untagging in it.
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---

With the suggested change to commit log in my previous email:

Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>

>  mm/frame_vector.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/frame_vector.c b/mm/frame_vector.c
> index c64dca6e27c2..c431ca81dad5 100644
> --- a/mm/frame_vector.c
> +++ b/mm/frame_vector.c
> @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
>  	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
>  		nr_frames = vec->nr_allocated;
>  
> +	start = untagged_addr(start);
> +
>  	down_read(&mm->mmap_sem);
>  	locked = 1;
>  	vma = find_vma_intersection(mm, start, start + 1);
>