Re: [OOPS] In __netif_receive_skb_core

From: Ivaylo Dimitrov
Date: Tue Jan 12 2016 - 02:16:26 EST

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.