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Commit 559fafb9 authored by xeb@mail.ru's avatar xeb@mail.ru Committed by David S. Miller
Browse files

gre: fix improper error handling 



Fix improper protocol err_handler, current implementation is fully
unapplicable and may cause kernel crash due to double kfree_skb.

Signed-off-by: default avatarDmitry Kozlov <xeb@mail.ru>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b0fe4a31

net/ipv4/gre.c

+6 −15
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/kmod.h>

#include <linux/skbuff.h>

#include <linux/in.h>

#include <linux/ip.h>

#include <linux/netdevice.h>

#include <linux/spinlock.h>

#include <net/protocol.h>
@@ -96,27 +97,17 @@ static int gre_rcv(struct sk_buff *skb) 
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;

	const struct iphdr *iph = (const struct iphdr *)skb->data;

	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;



	ver = skb->data[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;

	if (proto && proto->err_handler)

		proto->err_handler(skb, info);

	rcu_read_unlock();

	return;



drop_unlock:

	rcu_read_unlock();

drop:

	kfree_skb(skb);

}



static const struct net_protocol net_gre_protocol = {