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Message-ID: <201906240801.BE42EB3AA@keescook>
Date: Mon, 24 Jun 2019 08:01:39 -0700
From: Kees Cook <keescook@...omium.org>
To: Andrey Konovalov <andreyknvl@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org,
linux-media@...r.kernel.org, kvm@...r.kernel.org,
linux-kselftest@...r.kernel.org,
Catalin Marinas <catalin.marinas@....com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Will Deacon <will.deacon@....com>,
Mark Rutland <mark.rutland@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Yishai Hadas <yishaih@...lanox.com>,
Felix Kuehling <Felix.Kuehling@....com>,
Alexander Deucher <Alexander.Deucher@....com>,
Christian Koenig <Christian.Koenig@....com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Jens Wiklander <jens.wiklander@...aro.org>,
Alex Williamson <alex.williamson@...hat.com>,
Leon Romanovsky <leon@...nel.org>,
Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
Dave Martin <Dave.Martin@....com>,
Khalid Aziz <khalid.aziz@...cle.com>, enh <enh@...gle.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Christoph Hellwig <hch@...radead.org>,
Dmitry Vyukov <dvyukov@...gle.com>,
Kostya Serebryany <kcc@...gle.com>,
Evgeniy Stepanov <eugenis@...gle.com>,
Lee Smith <Lee.Smith@....com>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>,
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Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>,
Robin Murphy <robin.murphy@....com>,
Kevin Brodsky <kevin.brodsky@....com>,
Szabolcs Nagy <Szabolcs.Nagy@....com>
Subject: Re: [PATCH v18 11/15] IB/mlx4: untag user pointers in
mlx4_get_umem_mr
On Mon, Jun 24, 2019 at 04:32:56PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends kernel ABI to allow to pass
> tagged user pointers (with the top byte set to something else other than
> 0x00) as syscall arguments.
>
> mlx4_get_umem_mr() uses provided user pointers for vma lookups, which can
> only by done with untagged pointers.
>
> Untag user pointers in this function.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
-Kees
> ---
> drivers/infiniband/hw/mlx4/mr.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
> index 355205a28544..13d9f917f249 100644
> --- a/drivers/infiniband/hw/mlx4/mr.c
> +++ b/drivers/infiniband/hw/mlx4/mr.c
> @@ -378,6 +378,7 @@ static struct ib_umem *mlx4_get_umem_mr(struct ib_udata *udata, u64 start,
> * again
> */
> if (!ib_access_writable(access_flags)) {
> + unsigned long untagged_start = untagged_addr(start);
> struct vm_area_struct *vma;
>
> down_read(¤t->mm->mmap_sem);
> @@ -386,9 +387,9 @@ static struct ib_umem *mlx4_get_umem_mr(struct ib_udata *udata, u64 start,
> * cover the memory, but for now it requires a single vma to
> * entirely cover the MR to support RO mappings.
> */
> - vma = find_vma(current->mm, start);
> - if (vma && vma->vm_end >= start + length &&
> - vma->vm_start <= start) {
> + vma = find_vma(current->mm, untagged_start);
> + if (vma && vma->vm_end >= untagged_start + length &&
> + vma->vm_start <= untagged_start) {
> if (vma->vm_flags & VM_WRITE)
> access_flags |= IB_ACCESS_LOCAL_WRITE;
> } else {
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
--
Kees Cook
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