linux-kernel - Re: [OOPS] In __netif_receive_skb

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Message-ID: <5694A840.8030900@gmail.com>
Date:	Tue, 12 Jan 2016 09:16:16 +0200
From:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Salam Noureddine <noureddine@...sta.com>,
	"David S. Miller" <davem@...emloft.net>,
	Pali Rohár <pali.rohar@...il.com>,
	Network Development <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Sebastian Reichel <sre@...nel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: Re: [OOPS] In __netif_receive_skb_core



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