netdev - [PATCH net] netfilter: xt_TEE: fix NULL dereference

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Message-ID: <1445302921.30896.34.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 19 Oct 2015 18:02:01 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Pablo Neira Ayuso <pablo@...filter.org>
Cc:	netfilter-devel@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: [PATCH net] netfilter: xt_TEE: fix NULL dereference

From: Eric Dumazet <edumazet@...gle.com>

iptables -I INPUT ... -j TEE --gateway 10.1.2.3

<crash> because --oif was not specified

tee_tg_check() sets ->priv pointer to NULL in this case.

Fixes: bbde9fc1824a ("netfilter: factor out packet duplication for IPv4/IPv6")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/netfilter/xt_TEE.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
index fd980aa7715d..c5fdea18a9af 100644
--- a/net/netfilter/xt_TEE.c
+++ b/net/netfilter/xt_TEE.c
@@ -31,8 +31,9 @@ static unsigned int
 tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct xt_tee_tginfo *info = par->targinfo;
+	int oif = info->priv ? info->priv->oif : 0;
 
-	nf_dup_ipv4(skb, par->hooknum, &info->gw.in, info->priv->oif);
+	nf_dup_ipv4(skb, par->hooknum, &info->gw.in, oif);
 
 	return XT_CONTINUE;
 }
@@ -42,8 +43,9 @@ static unsigned int
 tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct xt_tee_tginfo *info = par->targinfo;
+	int oif = info->priv ? info->priv->oif : 0;
 
-	nf_dup_ipv6(skb, par->hooknum, &info->gw.in6, info->priv->oif);
+	nf_dup_ipv6(skb, par->hooknum, &info->gw.in6, oif);
 
 	return XT_CONTINUE;
 }


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