netdev - Re: [PATCH net] ipv6: add complete rcu protection around np->opt

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Date:	Wed, 02 Dec 2015 21:35:48 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	dvyukov@...gle.com, vyasevich@...il.com, kuznet@....inr.ac.ru,
	jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	edumazet@...gle.com, wdauchy@...il.com,
	rweikusat@...ileactivedefense.com, syzkaller@...glegroups.com,
	kcc@...gle.com, glider@...gle.com, sasha.levin@...cle.com
Subject: Re: [PATCH net] ipv6: add complete rcu protection around np->opt

On Wed, 2015-12-02 at 23:38 -0500, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Sun, 29 Nov 2015 19:37:57 -0800
> 
> > From: Eric Dumazet <edumazet@...gle.com>
> > 
> > This patch addresses multiple problems :
> > 
> > UDP/RAW sendmsg() need to get a stable struct ipv6_txoptions
> > while socket is not locked : Other threads can change np->opt
> > concurrently. Dmitry posted a syzkaller
> > (http://github.com/google/syzkaller) program desmonstrating
> > use-after-free.
> > 
> > Starting with TCP/DCCP lockless listeners, tcp_v6_syn_recv_sock()
> > and dccp_v6_request_recv_sock() also need to use RCU protection
> > to dereference np->opt once (before calling ipv6_dup_options())
> > 
> > This patch adds full RCU protection to np->opt
> > 
> > Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> 
> Applied and queued up for -stable.

Thanks David.

I will send a followup patch, as I missed the sctp part, now triggering
following sparse warnings.

  CHECK   net/sctp/ipv6.c
net/sctp/ipv6.c:223:41: warning: incorrect type in argument 4 (different address spaces)
net/sctp/ipv6.c:223:41:    expected struct ipv6_txoptions *opt
net/sctp/ipv6.c:223:41:    got struct ipv6_txoptions [noderef] <asn:4>*opt
net/sctp/ipv6.c:265:41: warning: incorrect type in argument 2 (different address spaces)
net/sctp/ipv6.c:265:41:    expected struct ipv6_txoptions const *opt
net/sctp/ipv6.c:265:41:    got struct ipv6_txoptions [noderef] <asn:4>*opt
net/sctp/ipv6.c:324:49: warning: incorrect type in argument 2 (different address spaces)
net/sctp/ipv6.c:324:49:    expected struct ipv6_txoptions const *opt
net/sctp/ipv6.c:324:49:    got struct ipv6_txoptions [noderef] <asn:4>*opt



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