brcmfmac: Avoid possible out-of-bounds read

In brcmf_p2p_notify_rx_mgmt_p2p_probereq(), chanspec is assigned before
the length of rxframe is validated.  This could lead to uninitialized
data being accessed (but not printed).  Since we already have a
perfectly good endian-swapped copy of rxframe->chanspec in ch.chspec,
and ch.chspec is not modified by decchspec(), avoid the extra
assignment and use ch.chspec in the debug print.

Suggested-by: Mattias Nissler <mnissler@chromium.org>
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c

@@ -1853,7 +1853,6 @@ s32 brcmf_p2p_notify_rx_mgmt_p2p_probereq(struct brcmf_if *ifp,
 	struct afx_hdl *afx_hdl = &p2p->afx_hdl;
 	struct brcmf_cfg80211_vif *vif = ifp->vif;
 	struct brcmf_rx_mgmt_data *rxframe = (struct brcmf_rx_mgmt_data *)data;
-	u16 chanspec = be16_to_cpu(rxframe->chanspec);
 	struct brcmu_chan ch;
 	u8 *mgmt_frame;
 	u32 mgmt_frame_len;
@@ -1906,7 +1905,7 @@ s32 brcmf_p2p_notify_rx_mgmt_p2p_probereq(struct brcmf_if *ifp,
 	cfg80211_rx_mgmt(&vif->wdev, freq, 0, mgmt_frame, mgmt_frame_len, 0);
 
 	brcmf_dbg(INFO, "mgmt_frame_len (%d) , e->datalen (%d), chanspec (%04x), freq (%d)\n",
-		  mgmt_frame_len, e->datalen, chanspec, freq);
+		  mgmt_frame_len, e->datalen, ch.chspec, freq);
 
 	return 0;
 }