linux-kernel - [PATCH] staging: rtl8723bs: avoid null pointer dereference on pmlmepriv

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Message-Id: <20170920173418.17570-1-colin.king@canonical.com>
Date:   Wed, 20 Sep 2017 18:34:18 +0100
From:   Colin King <colin.king@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans de Goede <hdegoede@...hat.com>,
        devel@...verdev.osuosl.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: rtl8723bs: avoid null pointer dereference on pmlmepriv

From: Colin Ian King <colin.king@...onical.com>

There is a check to see if pmlmepriv is null before vfree'ing
pmlmepriv->free_bss_buf hence implying pmlmepriv could potenially be
null. However, a previous call to rtw_free_mlme_priv_ie_data
can also dereference pmlmepriv, so move this call so that it is only
called if pmlmepriv non-null.

Detected by CoverityScan, CID#1077739 ("Dereference before null check")

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/staging/rtl8723bs/core/rtw_mlme.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index 37b683d4d1fa..0d94ced985c0 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -119,9 +119,8 @@ void rtw_free_mlme_priv_ie_data(struct mlme_priv *pmlmepriv)
 
 void _rtw_free_mlme_priv(struct mlme_priv *pmlmepriv)
 {
-	rtw_free_mlme_priv_ie_data(pmlmepriv);
-
 	if (pmlmepriv) {
+		rtw_free_mlme_priv_ie_data(pmlmepriv);
 		if (pmlmepriv->free_bss_buf) {
 			vfree(pmlmepriv->free_bss_buf);
 		}
-- 
2.14.1