Subject: Re: [OOPS] In __netif_receive_skb_core

From: Ivaylo Dimitrov <[email-masked]>
Date: Tue, 12 Jan 2016 09:16:16 +0200

On 12.01.2016 04:25, Eric Dumazet wrote:
> On Mon, 2016-01-11 at 18:21 -0800, Eric Dumazet wrote:
>> On Mon, 2016-01-11 at 17:19 -0800, Salam Noureddine wrote:
>>> It must be that skb->dev was changed to NULL inside of
>>> __netif_receive_skb_core, otherwise we would have crashed much
>>> earlier. Also, orig_dev is saved at the beginning. Possibly a device
>>> is layered on top of the original device.

Exactly (skb->dev was changed to NULL ...). Do you think it makes sense 
to put printks in various places in __netif_receive_skb_core to see 
after which function call skb->dev turns into NULL?

>
> OK please try this fix :
>
> diff --git a/net/phonet/af_phonet.c b/net/phonet/af_phonet.c
> index 10d42f3220ab..f925753668a7 100644
> --- a/net/phonet/af_phonet.c
> +++ b/net/phonet/af_phonet.c
> @@ -377,6 +377,10 @@ static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
>   	struct sockaddr_pn sa;
>   	u16 len;
>
> +	skb = skb_share_check(skb, GFP_ATOMIC);
> +	if (!skb)
> +		return NET_RX_DROP;
> +
>   	/* check we have at least a full Phonet header */
>   	if (!pskb_pull(skb, sizeof(struct phonethdr)))
>   		goto out;
>
>

That one fixes the oops, though I wonder if your previous patch is 
needed (I reverted it before testing the current). Unfortunately I don't 
have SIM card around to test GPRS connection with, will do it as soon as 
I find one and will report.

Thanks,
Ivo