netdev - Re: [PATCH v2 bpf-next 2/2] bpf: sockmap: initialize sg table entries properly

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Message-ID: <5d47187a-d17d-3ed9-55bb-7d961b48f9ee@gmail.com>
Date:   Thu, 29 Mar 2018 20:37:18 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        "David S . Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v2 bpf-next 2/2] bpf: sockmap: initialize sg table entries
 properly

On 03/29/2018 05:21 PM, Prashant Bhole wrote:
> When CONFIG_DEBUG_SG is set, sg->sg_magic is initialized in
> sg_init_table() and it is verified in sg api while navigating. We hit
> BUG_ON when magic check is failed.
> 
> In functions sg_tcp_sendpage and sg_tcp_sendmsg, the struct containing
> the scatterlist is already zeroed out. So to avoid extra memset, we
> use sg_init_marker() to initialize sg_magic.
> 
> Fixed following things:
> - In bpf_tcp_sendpage: initialize sg using sg_init_marker
> - In bpf_tcp_sendmsg: Replace sg_init_table with sg_init_marker
> - In bpf_tcp_push: Replace memset with sg_init_table where consumed
>   sg entry needs to be re-initialized.
> 
> Signed-off-by: Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
> ---
>  kernel/bpf/sockmap.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 

Acked-by: John Fastabend <john.fastabend@...il.com>