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Subject: Re: net/icmp: null-ptr-deref in icmp6_send
To: Cong Wang <xiyou.wangcong@gmail.com>,
        Andrey Konovalov <andreyknvl@google.com>
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Cc: "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        James Morris <jmorris@namei.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
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From: David Ahern <dsa@cumulusnetworks.com>
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Date: Tue, 22 Nov 2016 22:10:37 -0500
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On 11/22/16 1:11 PM, Cong Wang wrote:
> I have no idea what commit 5d41ce29e tried to fix, but we already
> use skb->dev a few lines before l3mdev_master_ifindex(), so I don't
> understand why skb->dev could be NULL, maybe just for vrf dev?

skb->dev can be null depending on when icmp6_send / icmpv6_send is called. Clearly I missed the ipv6_parse_hopopts -> icmpv6_param_prob path. I'll send a fix when I get back from PTO.