From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Kozlov Subject: [PATCH net-2.6] gre: fix improper error handling Date: Fri, 22 Jul 2011 13:26:10 +0400 Message-ID: <201107221326.10597.xeb@mail.ru> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: davem@davemloft.net Return-path: Received: from fallback8.mail.ru ([94.100.176.136]:60531 "EHLO fallback8.mail.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922Ab1GVJff (ORCPT ); Fri, 22 Jul 2011 05:35:35 -0400 Received: from smtp12.mail.ru (smtp12.mail.ru [94.100.176.89]) by fallback8.mail.ru (mPOP.Fallback_MX) with ESMTP id CDA4713C2873 for ; Fri, 22 Jul 2011 13:26:40 +0400 (MSD) Sender: netdev-owner@vger.kernel.org List-ID: Fix improper protocol err_handler, current implementation is fully unapplicable and may cause kernel crash due to double kfree_skb. Signed-off-by: Dmitry Kozlov -- net/ipv4/gre.c | 23 +++++++---------------- 1 files changed, 7 insertions(+), 16 deletions(-) diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c index c6933f2..a8126fe 100644 --- a/net/ipv4/gre.c +++ b/net/ipv4/gre.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -97,27 +98,17 @@ drop: static void gre_err(struct sk_buff *skb, u32 info) { const struct gre_protocol *proto; - u8 ver; - - if (!pskb_may_pull(skb, 12)) - goto drop; - - ver = skb->data[1]&0x7f; + const struct iphdr *iph = (const struct iphdr *)skb->data; + u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; + if (ver >= GREPROTO_MAX) - goto drop; + return; rcu_read_lock(); proto = rcu_dereference(gre_proto[ver]); - if (!proto || !proto->err_handler) - goto drop_unlock; - proto->err_handler(skb, info); - rcu_read_unlock(); - return; - -drop_unlock: + if (proto && proto->err_handler) + proto->err_handler(skb, info); rcu_read_unlock(); -drop: - kfree_skb(skb); } static const struct net_protocol net_gre_protocol = {