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([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id p34sm4428128pgb.18.2019.03.15.13.03.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Mar 2019 13:03:32 -0700 (PDT) Subject: Re: [PATCH v11 08/14] net, arm64: untag user pointers in tcp_zerocopy_receive To: Andrey Konovalov , Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy References: <56d3373c1c5007d776fcd5de4523f4b9da341fb6.1552679409.git.andreyknvl@google.com> From: Eric Dumazet Message-ID: <04c5b2de-7fde-7625-9d42-228160879ea0@gmail.com> Date: Fri, 15 Mar 2019 13:03:30 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <56d3373c1c5007d776fcd5de4523f4b9da341fb6.1552679409.git.andreyknvl@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/15/2019 12:51 PM, 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. > > tcp_zerocopy_receive() 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 > --- > net/ipv4/tcp.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index 6baa6dc1b13b..89db3b4fc753 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -1758,6 +1758,8 @@ static int tcp_zerocopy_receive(struct sock *sk, > int inq; > int ret; > > + address = untagged_addr(address); > + > if (address & (PAGE_SIZE - 1) || address != zc->address) The second test will fail, if the top bits are changed in address but not in zc->address > return -EINVAL; > >