Subject: Re: [PATCH] ip_gre: fix kernel panic with icmp_dest_unreach

From: Daniel Petre <[email-masked]>
Date: Fri, 24 May 2013 12:40:02 +0300

On 05/23/2013 08:10 PM, Eric Dumazet wrote:
> On Thu, 2013-05-23 at 08:53 -0700, Eric Dumazet wrote:
>> On Thu, 2013-05-23 at 11:47 +0300, Daniel Petre wrote:
>>
>>>
>>> Hello again Eric,
>>> we applied the little patch from:
>>> http://lkml.indiana.edu/hypermail/linux/kernel/1007.0/00961.html
>>> we have flapped the link few times and everything recovered smooth.
>>>
>>
>> Thats a very good catch, now we have to fix the bug at the right place.
> 
> 
> Please try the following patch :

we have compiled it, tested it few times and.. nothing evil happens anymore!

> 
> diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
> index 91d66db..563358e 100644
> --- a/net/ipv4/ip_gre.c
> +++ b/net/ipv4/ip_gre.c
> @@ -795,6 +795,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
>  
>  	if (dev->type == ARPHRD_ETHER)
>  		IPCB(skb)->flags = 0;
> +	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
>  
>  	if (dev->header_ops && dev->type == ARPHRD_IPGRE) {
>  		gre_hlen = 0;
> @@ -952,7 +953,6 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
>  	skb_push(skb, gre_hlen);
>  	skb_reset_network_header(skb);
>  	skb_set_transport_header(skb, sizeof(*iph));
> -	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
>  	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
>  			      IPSKB_REROUTED);
>  	skb_dst_drop(skb);
> 
>