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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Wed, 9 Oct 2019 15:49:37 -0700
Message-ID: <CAADnVQ++EF8oEzVvfx=0XHiv_YccHr1gCxzRs5GYGk5uB0CmuQ@mail.gmail.com>
Subject: Re: [PATCH bpf v2] libbpf: fix passing uninitialized bytes to setsockopt
To:     Ilya Maximets <i.maximets@ovn.org>
Cc:     Network Development <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "David S . Miller" <davem@davemloft.net>,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>
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On Wed, Oct 9, 2019 at 9:49 AM Ilya Maximets <i.maximets@ovn.org> wrote:
>
> 'struct xdp_umem_reg' has 4 bytes of padding at the end that makes
> valgrind complain about passing uninitialized stack memory to the
> syscall:
>
>   Syscall param socketcall.setsockopt() points to uninitialised byte(s)
>     at 0x4E7AB7E: setsockopt (in /usr/lib64/libc-2.29.so)
>     by 0x4BDE035: xsk_umem__create@@LIBBPF_0.0.4 (xsk.c:172)
>   Uninitialised value was created by a stack allocation
>     at 0x4BDDEBA: xsk_umem__create@@LIBBPF_0.0.4 (xsk.c:140)
>
> Padding bytes appeared after introducing of a new 'flags' field.
> memset() is required to clear them.
>
> Fixes: 10d30e301732 ("libbpf: add flags to umem config")
> Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

Applied. Thanks