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Subject: Re: [PATCHv2 1/1] mac80211: fix WPA with VLAN on AP side with ps-sta
From: Johannes Berg <johannes@sipsolutions.net>
To: michael-dev <michael-dev@fami-braun.de>
Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org,
	projekt-wlan@fem.tu-ilmenau.de
Date: Tue, 12 Feb 2013 18:45:39 +0100
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On Tue, 2013-02-12 at 18:42 +0100, michael-dev wrote:

> >> -		if (!ieee80211_tx_prepare(sdata, &tx, skb))
> >> +		frame_sdata = IEEE80211_DEV_TO_SUB_IF(skb->dev);
> >> +		if (!ieee80211_tx_prepare(frame_sdata, &tx, skb))
> >>  			break;
> > 
> > This can now crash the machine.
> 
> why? when?

There's no guarantee that the VLAN interface isn't destroyed while the
frame is stuck on the buffer queue.

> What would be a better approach?

This is probably fine, but incomplete -- frames for a VLAN need to be
removed from the PS queue when it goes down.

johannes