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[209.85.220.65]) by mx.google.com with SMTPS id 3sor12392175plq.28.2019.05.06.07.15.32 for (Google Transport Security); Mon, 06 May 2019 07:15:32 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=RwIwMiF8; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OW9r981uG4q4mCEE3eviMpvcgNrP8ztSBy/V22TuEyU=; b=RwIwMiF88+Wz2lyiiiRFLD0DtzmtPhSYctT7DECXSVGGsMCqqEywraKb1VVIDK0D+6 e05K/iAAJcE9yRHQNbEvq9ePWUxNo3jMQ16tSsOGtmWiuiuGjYTIKZn3RWyGJN1L7rxH JWCib8njn+v5Gl74GjdEjnavoToExJWkPKuLN2usGUeeVQU1cj6afqv3AP+Szx9d1YbR /iYb1mW4rEJXqf/1doCy1zenFphH/aiHoOYrBoxPgEK3EUfKzOGpHL63KMDfpfhEfnGD SAWo20WeW5Qs/kAhFHEaSxMs4rZb4+Da05bz1k2JR3ScMW8GRukA/aJ+BvUhLbhKhimD bg2g== X-Google-Smtp-Source: APXvYqyWDp8mHq4mu+m9PaBcR4hr0UfLsUgs2S/OxvEKrdiWi6A7iqRf42KWhYp4nRTNFO6VlU1AYWwzebl0ku93GlI= X-Received: by 2002:a17:902:7783:: with SMTP id o3mr32385898pll.159.1557152131315; Mon, 06 May 2019 07:15:31 -0700 (PDT) MIME-Version: 1.0 References: <7d3b28689d47c0fa1b80628f248dbf78548da25f.1556630205.git.andreyknvl@google.com> <20190503165646.GK55449@arrakis.emea.arm.com> In-Reply-To: <20190503165646.GK55449@arrakis.emea.arm.com> From: Andrey Konovalov Date: Mon, 6 May 2019 16:15:20 +0200 Message-ID: Subject: Re: [PATCH v14 10/17] fs, arm64: untag user pointers in fs/userfaultfd.c To: Catalin Marinas Cc: Linux ARM , Linux Memory Management List , LKML , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Kuehling@google.com, Felix , Deucher@google.com, Alexander , Koenig@google.com, Christian , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 3, 2019 at 6:56 PM Catalin Marinas wrote: > > On Tue, Apr 30, 2019 at 03:25:06PM +0200, 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. > > > > userfaultfd_register() and userfaultfd_unregister() use provided user > > pointers for vma lookups, which can only by done with untagged pointers. > > > > Untag user pointers in these functions. > > > > Signed-off-by: Andrey Konovalov > > --- > > fs/userfaultfd.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > > index f5de1e726356..fdee0db0e847 100644 > > --- a/fs/userfaultfd.c > > +++ b/fs/userfaultfd.c > > @@ -1325,6 +1325,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > > goto out; > > } > > > > + uffdio_register.range.start = > > + untagged_addr(uffdio_register.range.start); > > + > > ret = validate_range(mm, uffdio_register.range.start, > > uffdio_register.range.len); > > if (ret) > > @@ -1514,6 +1517,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > > if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) > > goto out; > > > > + uffdio_unregister.start = untagged_addr(uffdio_unregister.start); > > + > > ret = validate_range(mm, uffdio_unregister.start, > > uffdio_unregister.len); > > if (ret) > > Wouldn't it be easier to do this in validate_range()? There are a few > more calls in this file, though I didn't check whether a tagged address > would cause issues. Yes, I think it makes more sense, will do in v15, thanks! > > -- > Catalin