linux-kernel - Re: memory leak in do_ipv6

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Date:	Tue, 01 Dec 2015 06:38:43 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	"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>,
	Vlad Yasevich <vyasevich@...il.com>,
	Neil Horman <nhorman@...driver.com>,
	linux-sctp@...r.kernel.org, syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: memory leak in do_ipv6_setsockopt

On Tue, 2015-12-01 at 15:24 +0100, Daniel Borkmann wrote:
> On 12/01/2015 03:16 PM, Eric Dumazet wrote:
> > On Tue, 2015-12-01 at 15:07 +0100, Daniel Borkmann wrote:
> >
> >> Yeah, we miss inet6_destroy_sock() in SCTP. :-(
> >>
> >> Looks good to me.
> >
> > OK, I will send a formal (and tested ;) ) patch.
> 
> I was shortly wondering whether there could be a use-after-free by
> doing this after sctp_destroy_sock() due to the sctp_endpoint_destroy()
> that would eventually drop a ref on the socket, but the endpoint holds
> a separate ref, so we should be good.
> 

More generically ->destroy() caller must keep a reference on the socket.

inet_csk_destroy_sock() for example uses sk after

sk->sk_prot->destroy(sk);



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