From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756199Ab3ILSBr (ORCPT ); Thu, 12 Sep 2013 14:01:47 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57160 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755911Ab3ILR72 (ORCPT ); Thu, 12 Sep 2013 13:59:28 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Eric Dumazet , Eric Dumazet , Jiri Benc , "David S. Miller" Subject: [ 41/46] net: ipv6: tcp: fix potential use after free in tcp_v6_do_rcv Date: Thu, 12 Sep 2013 10:58:52 -0700 Message-Id: <20130912175725.418006506@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20130912175721.001906199@linuxfoundation.org> References: <20130912175721.001906199@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 3a1c756590633c0e86df606e5c618c190926a0df ] In tcp_v6_do_rcv() code, when processing pkt options, we soley work on our skb clone opt_skb that we've created earlier before entering tcp_rcv_established() on our way. However, only in condition ... if (np->rxopt.bits.rxtclass) np->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(skb)); ... we work on skb itself. As we extract every other information out of opt_skb in ipv6_pktoptions path, this seems wrong, since skb can already be released by tcp_rcv_established() earlier on. When we try to access it in ipv6_hdr(), we will dereference freed skb. [ Bug added by commit 4c507d2897bd9b ("net: implement IP_RECVTOS for IP_PKTOPTIONS") ] Signed-off-by: Daniel Borkmann Cc: Eric Dumazet Acked-by: Eric Dumazet Acked-by: Jiri Benc Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/tcp_ipv6.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1426,7 +1426,7 @@ ipv6_pktoptions: if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit; if (np->rxopt.bits.rxtclass) - np->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(skb)); + np->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(opt_skb)); if (ipv6_opt_accepted(sk, opt_skb)) { skb_set_owner_r(opt_skb, sk); opt_skb = xchg(&np->pktoptions, opt_skb);