netdev - Re: [PATCH net v2] tcp: prevent fetching dst twice in early demux code

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: <1427121564.25985.69.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 23 Mar 2015 07:39:24 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Michal Kubecek <mkubecek@...e.cz>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH net v2] tcp: prevent fetching dst twice in early demux
 code

On Mon, 2015-03-23 at 15:14 +0100, Michal Kubecek wrote:
> On s390x, gcc 4.8 compiles this part of tcp_v6_early_demux()
> 
>         struct dst_entry *dst = sk->sk_rx_dst;
> 
>         if (dst)
>                 dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie);
> 
> to code reading sk->sk_rx_dst twice, once for the test and once for
> the argument of ip6_dst_check() (dst_check() is inline). This allows
> ip6_dst_check() to be called with null first argument, causing a crash.
> 
> Protect sk->sk_rx_dst access by READ_ONCE() both in IPv4 and IPv6
> TCP early demux code.
> 
> Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.")
> Fixes: c7109986db3c ("ipv6: Early TCP socket demux")
> Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>

Thanks Michal


--
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