[PATCH 4.1 15/78] rtlwifi: Fix NULL dereference when PCI driver used as an AP

[Greg Kroah-Hartman]

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Luis Felipe Dominguez Vega <lfdominguez@xxxxxxxx>

commit 7c62940165e9ae4004ce4e6b5117330bab94df68 upstream.

In commit 33511b157bbcebaef853cc1811992b664a2e5862 ("rtlwifi: add support to
send beacon frame"), the mechanism for sending beacons was established. That
patch works correctly for rtl8192cu, but there is a possibility of getting
the following warnings in the PCI drivers:

WARNING: CPU: 1 PID: 2439 at net/mac80211/driver-ops.h:12
ieee80211_bss_info_change_notify+0x179/0x1d0 [mac80211]()
wlp5s0:  Failed check-sdata-in-driver check, flags: 0x0

The warning is followed by a NULL pointer dereference as follows:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000006
IP: [<ffffffffc073998e>] rtl_get_tcb_desc+0x5e/0x760 [rtlwifi]

This problem was reported at http://thread.gmane.org/gmane.linux.kernel.wireless.general/138645,
but no solution was found at that time.

The problem was also reported at https://bugzilla.kernel.org/show_bug.cgi?id=9744
and this solution was developed and tested there.

The USB driver works with a NULL final argument in the adapter_tx() callback;
however, the PCI drivers need a struct rtl_tcb_desc in that position.

Fixes: 33511b157bbc ("rtlwifi: add support to send beacon frame.")
Signed-off-by: Luis Felipe Dominguez Vega <lfdominguez@xxxxxxxx>
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/wireless/rtlwifi/core.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/rtlwifi/core.c
+++ b/drivers/net/wireless/rtlwifi/core.c
@@ -1015,9 +1015,12 @@ static void send_beacon_frame(struct iee
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
 	struct sk_buff *skb = ieee80211_beacon_get(hw, vif);
+	struct rtl_tcb_desc tcb_desc;
 
-	if (skb)
-		rtlpriv->intf_ops->adapter_tx(hw, NULL, skb, NULL);
+	if (skb) {
+		memset(&tcb_desc, 0, sizeof(struct rtl_tcb_desc));
+		rtlpriv->intf_ops->adapter_tx(hw, NULL, skb, &tcb_desc);
+	}
 }
 
 static void rtl_op_bss_info_changed(struct ieee80211_hw *hw,


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