linux-kernel - Re: [PATCH bpf] libbpf: fix passing uninitialized bytes to setsockopt

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Message-ID: <50f76b97-2be6-6976-36ec-bfb88afc6009@ovn.org>
Date:   Sun, 13 Oct 2019 12:01:15 +0200
From:   Ilya Maximets <i.maximets@....org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Ilya Maximets <i.maximets@....org>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Jonathan Lemon <jonathan.lemon@...il.com>
Subject: Re: [PATCH bpf] libbpf: fix passing uninitialized bytes to setsockopt

On 13.10.2019 6:59, Alexei Starovoitov wrote:
> On Sat, Oct 12, 2019 at 9:52 PM Ilya Maximets <i.maximets@....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.
>>
>> Fixes: 10d30e301732 ("libbpf: add flags to umem config")
>> Signed-off-by: Ilya Maximets <i.maximets@....org>
> 
> Something is not right with (e|g)mail.
> This is 3rd email I got with the same patch.
> First one (the one that was applied) was 3 days ago.
> 

I'm sorry.  I don't know why the mail server started re-sending
these e-mails.  I'm receiving them too.

That is strange.

Best regards, Ilya Maximets.