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gre: fix improper error handling

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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 <xeb@mail.ru>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
xeb@mail.ru
2011-07-22 20:49:40 +00:00
committed by David S. Miller
parent b0fe4a3184
commit 559fafb94a
1 changed files with 6 additions and 15 deletions
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19
net/ipv4/gre.c
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@@ -15,6 +15,7 @@
#include <linux/kmod.h> #include <linux/kmod.h>
#include <linux/skbuff.h> #include <linux/skbuff.h>
#include <linux/in.h> #include <linux/in.h>
#include <linux/ip.h>
#include <linux/netdevice.h> #include <linux/netdevice.h>
#include <linux/spinlock.h> #include <linux/spinlock.h>
#include <net/protocol.h> #include <net/protocol.h>
@@ -96,27 +97,17 @@ drop:
static void gre_err(struct sk_buff *skb, u32 info) static void gre_err(struct sk_buff *skb, u32 info)
{ {
const struct gre_protocol *proto; const struct gre_protocol *proto;
u8 ver; const struct iphdr *iph = (const struct iphdr *)skb->data;
u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
if (!pskb_may_pull(skb, 12))
goto drop;
ver = skb->data[1]&0x7f;
if (ver >= GREPROTO_MAX) if (ver >= GREPROTO_MAX)
goto drop; return;
rcu_read_lock(); rcu_read_lock();
proto = rcu_dereference(gre_proto[ver]); proto = rcu_dereference(gre_proto[ver]);
if (!proto || !proto->err_handler) if (proto && proto->err_handler)
goto drop_unlock;
proto->err_handler(skb, info); proto->err_handler(skb, info);
rcu_read_unlock(); rcu_read_unlock();
return;
drop_unlock:
rcu_read_unlock();
drop:
kfree_skb(skb);
} }
static const struct net_protocol net_gre_protocol = { static const struct net_protocol net_gre_protocol = {