linux-kernel - Re: [PATCH] net/dccp: fix use after free in tw_timer

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Date:   Tue, 21 Feb 2017 13:24:49 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     aryabinin@...tuozzo.com
Cc:     gerrit@....abdn.ac.uk, dccp@...r.kernel.org, dvyukov@...gle.com,
        edumazet@...gle.com, xiyou.wangcong@...il.com,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
        syzkaller@...glegroups.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/dccp: fix use after free in tw_timer_handler()

From: David Miller <davem@...emloft.net>
Date: Tue, 21 Feb 2017 13:23:51 -0500 (EST)

> From: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Date: Tue, 21 Feb 2017 14:27:40 +0300
> 
>> DCCP doesn't purge timewait sockets on network namespace shutdown.
>> So, after net namespace destroyed we could still have an active timer
>> which will trigger use after free in tw_timer_handler():
>  ...
>> Add .exit_batch hook to dccp_v4_ops()/dccp_v6_ops() which will purge
>> timewait sockets on net namespace destruction and prevent above issue.
>> 
>> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
>> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> 
> Applied and queued up for -stable, thanks.

Actually, this doesn't even compile.  Please fix this up and resubmit:

net/dccp/ipv4.c: In function ‘dccp_v4_exit_batch’:
net/dccp/ipv4.c:1022:34: warning: passing argument 2 of ‘inet_twsk_purge’ makes integer from pointer without a cast [-Wint-conversion]
  inet_twsk_purge(&dccp_hashinfo, &dccp_death_row, AF_INET);
                                  ^
In file included from ./include/linux/dccp.h:14:0,
                 from net/dccp/ipv4.c:13:
./include/net/inet_timewait_sock.h:118:6: note: expected ‘int’ but argument is of type ‘struct inet_timewait_death_row *’
 void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family);
      ^
net/dccp/ipv4.c:1022:2: error: too many arguments to function ‘inet_twsk_purge’
  inet_twsk_purge(&dccp_hashinfo, &dccp_death_row, AF_INET);
  ^