[PATCH v2] staging: rtl8723bs: fix null dereference in find_network

[Ethan Tidmore <ethantidmore06@gmail.com>]

The variable pwlan has the possibility of being NULL when passed into 
rtw_free_network_nolock() which would later dereference the variable.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable@vger.kernel.org
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
---
v2:
- Included more context to demonstrate possible null dereference.

 drivers/staging/rtl8723bs/core/rtw_mlme.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index 8e1e1c97f0c4..e734d35c11a9 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -828,22 +828,24 @@ static void rtw_reset_rx_info(struct debug_priv *pdbgpriv)
 	pdbgpriv->dbg_rx_ampdu_window_shift_cnt = 0;
 }
 
 static void find_network(struct adapter *adapter)
 {
 	struct wlan_network *pwlan = NULL;
 	struct	mlme_priv *pmlmepriv = &adapter->mlmepriv;
 	struct wlan_network *tgt_network = &pmlmepriv->cur_network;
 
 	pwlan = rtw_find_network(&pmlmepriv->scanned_queue, tgt_network->network.mac_address);
-	if (pwlan)
-		pwlan->fixed = false;
+	if (!pwlan)
+		return;
+
+	pwlan->fixed = false;
 
 	if (check_fwstate(pmlmepriv, WIFI_ADHOC_MASTER_STATE) &&
 	    (adapter->stapriv.asoc_sta_count == 1))
 		rtw_free_network_nolock(adapter, pwlan);
 }
 
 /* rtw_free_assoc_resources: the caller has to lock pmlmepriv->lock */
 void rtw_free_assoc_resources(struct adapter *adapter, int lock_scanned_queue)
 {
 	struct	mlme_priv *pmlmepriv = &adapter->mlmepriv;
-- 
2.52.0