Re: [PATCH 2/4] wan/hdlc_x25: fix skb handling

[David Miller]

From: Martin Schiller <ms@xxxxxxxxxx>
Date: Fri, 05 Apr 2019 08:56:44 +0200

> On 2019-04-05 02:32, David Miller wrote:
>> From: Martin Schiller <ms@xxxxxxxxxx>
>> Date: Wed,  3 Apr 2019 07:01:16 +0200
>> 
>>>  	/* X.25 to LAPB */
>>>  	switch (skb->data[0]) {
>>>  	case X25_IFACE_DATA:	/* Data to be transmitted */
>>> -		skb_pull(skb, 1);
>>> -		if ((result = lapb_data_request(dev, skb)) != LAPB_OK)
>>> -			dev_kfree_skb(skb);
>>> -		return NETDEV_TX_OK;
>>> +		skbn = skb_copy(skb, GFP_ATOMIC);
>>> +		skb_pull(skbn, 1);
>>> +		skb_reset_network_header(skbn);
>>> +		if ((result = lapb_data_request(dev, skbn)) != LAPB_OK)
>>> +			dev_kfree_skb(skbn);
>> This leaks 'skb'.
> 
> What exactly do you mean?
> 'skb' will get freed at the end of x25_xmit() function:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wan/hdlc_x25.c#n129

Then why was it freed here in the original code?