Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200727033810.28883-1-gaurav1086@gmail.com> <20200728021348.4116-1-gaurav1086@gmail.com>
In-Reply-To: <20200728021348.4116-1-gaurav1086@gmail.com>
From:   Cong Wang <xiyou.wangcong@gmail.com>
Date:   Mon, 27 Jul 2020 20:12:53 -0700
Message-ID: <CAM_iQpWbT18cRfDc2f1wVUrS6QpOmPrZwBqaitD7545-itijfg@mail.gmail.com>
Subject: Re: [PATCH] [net/ipv6] ip6_output: Add ipv6_pinfo null check
To:     Gaurav Singh <gaurav1086@gmail.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>,
        "open list:NETWORKING [IPv4/IPv6]" <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Jul 27, 2020 at 7:14 PM Gaurav Singh <gaurav1086@gmail.com> wrote:
>
> Add return to fix build issue. Haven't reproduced this issue at
> my end.
>
> My hypothesis is this: In function: ip6_xmit(), we have
> const struct ipv6_pinfo *np = inet6_sk(sk); which returns NULL.
>
> Further down the function, there's a check:
> if (np) hlimit = hp->htop_limit

This check exists before git history, at that time 'sk' could be NULL,
hence 'np', so it does not mean it is still necessary now.

I looked at all callers of ip6_xmit(), I don't see how it is called with
a non-full socket, neither 'sk' could be NULL after
commit b30bd282cbf5c46247a279a2e8d2aae027d9f1bf
("[IPV6]: ip6_xmit: remove unnecessary NULL ptr check").

Thanks.