netdev - Re: net/tcp: null-ptr-deref in __inet_lookup_listener/inet_exact_dif

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Message-ID: <f92b8a3e-9318-90c4-009a-15da3897ff6b@cumulusnetworks.com>
Date:   Wed, 2 Nov 2016 12:31:20 -0600
From:   David Ahern <dsa@...ulusnetworks.com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net/tcp: null-ptr-deref in
 __inet_lookup_listener/inet_exact_dif_match

On 11/2/16 11:21 AM, Eric Dumazet wrote:
> Thanks for your report.
> 
> David, please take a look.
> 
> TCP MD5 can call __inet_lookup_listener() with a NULL skb.

interesting. I did not test md5 before sending, but doing so now I am not able to trigger the panic with any combination of passwords - correct, wrong, none, no listener, etc. perhaps I am missing a sysctl setting.

Will send a fix. I see the call to __inet_lookup_listener with null skb.

> 
> Bug added in commit a04a480d4392ea6efd117be2de564117b2a009c0