Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757751Ab3JJQCF (ORCPT ); Thu, 10 Oct 2013 12:02:05 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52867 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756094Ab3JJPso (ORCPT ); Thu, 10 Oct 2013 11:48:44 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Daniel Borkmann , Eric Dumazet , "David S. Miller" , Kamal Mostafa Subject: [PATCH 027/104] net: ipv6: tcp: fix potential use after free in tcp_v6_do_rcv Date: Thu, 10 Oct 2013 08:41:15 -0700 Message-Id: <1381419752-29733-28-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1381419752-29733-1-git-send-email-kamal@canonical.com> References: <1381419752-29733-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2041 Lines: 55 3.8.13.11 -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 [ kamal: backport to 3.8 ] Signed-off-by: Kamal Mostafa --- net/ipv6/tcp_ipv6.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 4cc834a..2eb71b4 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1468,7 +1468,7 @@ 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_tclass(ipv6_hdr(skb)); + np->rcv_tclass = ipv6_tclass(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); -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/