Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754408Ab2JNOmP (ORCPT ); Sun, 14 Oct 2012 10:42:15 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46160 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754278Ab2JNOmF (ORCPT ); Sun, 14 Oct 2012 10:42:05 -0400 Message-Id: <20121014143552.169789826@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 14 Oct 2012 15:37:49 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jozsef Kadlecsik , Pablo Neira Ayuso Subject: [ 136/147] netfilter: nf_ct_ipv4: packets with wrong ihl are invalid In-Reply-To: <20121014143533.742627615@decadent.org.uk> X-SA-Exim-Connect-IP: 77.75.106.1 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2204 Lines: 61 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jozsef Kadlecsik commit 07153c6ec074257ade76a461429b567cff2b3a1e upstream. It was reported that the Linux kernel sometimes logs: klogd: [2629147.402413] kernel BUG at net / netfilter / nf_conntrack_proto_tcp.c: 447! klogd: [1072212.887368] kernel BUG at net / netfilter / nf_conntrack_proto_tcp.c: 392 ipv4_get_l4proto() in nf_conntrack_l3proto_ipv4.c and tcp_error() in nf_conntrack_proto_tcp.c should catch malformed packets, so the errors at the indicated lines - TCP options parsing - should not happen. However, tcp_error() relies on the "dataoff" offset to the TCP header, calculated by ipv4_get_l4proto(). But ipv4_get_l4proto() does not check bogus ihl values in IPv4 packets, which then can slip through tcp_error() and get caught at the TCP options parsing routines. The patch fixes ipv4_get_l4proto() by invalidating packets with bogus ihl value. The patch closes netfilter bugzilla id 771. Signed-off-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso Signed-off-by: Ben Hutchings --- net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c index 750b06a..cf73cc7 100644 --- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c +++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c @@ -84,6 +84,14 @@ static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff, *dataoff = nhoff + (iph->ihl << 2); *protonum = iph->protocol; + /* Check bogus IP headers */ + if (*dataoff > skb->len) { + pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: " + "nhoff %u, ihl %u, skblen %u\n", + nhoff, iph->ihl << 2, skb->len); + return -NF_ACCEPT; + } + return NF_ACCEPT; } -- 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/