netdev - Re: [PATCH net 3/3] ipv6: Fix dst_entry refcnt bugs in ip6

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1441142818.8932.185.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Tue, 01 Sep 2015 14:26:58 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Martin KaFai Lau <kafai@...com>
Cc:	netdev <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Kernel Team <kernel-team@...com>
Subject: Re: [PATCH net 3/3] ipv6: Fix dst_entry refcnt bugs in ip6_tunnel

On Tue, 2015-09-01 at 13:55 -0700, Martin KaFai Lau wrote:
> On Tue, Sep 01, 2015 at 01:14:20PM -0700, Eric Dumazet wrote:
> > It should not be a problem. refcnt is taken when/if necessary (skb
> > queued on a qdisc for example)
> >
> > We have other uses of skb_dst_set_noref()
> >
> > Please describe the problem ?
> The current ip6_tnl_dst_get() does not take the dst refcnt.
> 
> If the dst is released after ip6_tnl_dst_get() and before
> skb_dst_set_noref(), would it cause an issue?

We are under rcu here, and a dst in a cache is protected by RCU by
definition.

skb_dst_set_noref() has following debugging clause, does it trigger for
you ?

WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html