netdev - Re: net/ipv6: potential deadlock in do_ipv6

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Date:   Sun, 16 Oct 2016 11:50:26 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Baozeng Ding <sploving1@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: net/ipv6: potential deadlock in do_ipv6_setsockopt

On Sun, Oct 16, 2016 at 6:34 AM, Baozeng Ding <sploving1@...il.com> wrote:
>  Possible unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock([  165.136033] sk_lock-AF_INET6
> );
>                                lock([  165.136033] rtnl_mutex
> );
>                                lock([  165.136033] sk_lock-AF_INET6
> );
>   lock([  165.136033] rtnl_mutex
> );
>
>  *** DEADLOCK ***

This is caused by the conditional rtnl locking in do_ipv6_setsockopt().
It looks like we miss the case of IPV6_ADDRFORM.

Please try the attached patch.

View attachment "ipv6-setsockopt.diff" of type "text/plain" (1379 bytes)