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

Greg Kroah-Hartman
2015-09-11T23:04:29Z

From: Luis Felipe Dominguez Vega <lfdominguez@nauta.cu>

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@nauta.cu>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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,