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Subject: Re: [PATCHv4] mac80211: fix A-MSDU outer SA/DA
From: Johannes Berg <johannes@sipsolutions.net>
To: Felix Fietkau <nbd@nbd.name>,
        Michael Braun <michael-dev@fami-braun.de>
Cc: linux-wireless@vger.kernel.org, projekt-wlan@fem.tu-ilmenau.de
Date: Thu, 13 Oct 2016 09:23:51 +0200
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> > +     /* h_80211_src/dst is addr* field within hdr */
> > +     h_80211_src = data + fast_tx->sa_offs;
> > +     h_80211_dst = data + fast_tx->da_offs;

[...]

> > +	if (bssid && ieee80211_has_fromds(hdr->frame_control))
> > +		memcpy(h_80211_src, bssid, ETH_ALEN);
> > +
> > +	if (bssid && ieee80211_has_tods(hdr->frame_control))
> > +		memcpy(h_80211_dst, bssid, ETH_ALEN);

> I think this is probably wrong for 4-addr, since there both FromDS
> and ToDS are set. Maybe you should use !ieee80211_has_tods instead of
> ieee80211_has_fromds and vice versa.

It helps to look at the spec ;-)

For 4-addr frames, dest/src are addr 3/4 respectively, and in the spec
both *should* actually be set to the BSSID.

It's kinda pointless to be doing that and using a 4-addr frame here,
but I suppose it would be expected by the receiver in 4-addr mode, so
makes some sense.

johannes