linux-kernel - [PATCH] staging: rtl8188eu: avoid a null dereference on pmlmepriv

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Message-Id: <20171020184024.8035-1-colin.king@canonical.com>
Date:   Fri, 20 Oct 2017 20:40:24 +0200
From:   Colin King <colin.king@...onical.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Gargi Sharma <gs051095@...il.com>, devel@...verdev.osuosl.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: rtl8188eu: avoid a null dereference on pmlmepriv

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

There is a check on pmlmepriv before dereferencing it when
vfree'ing pmlmepriv->free_bss_buf however the previous call
to rtw_free_mlme_priv_ie_data deferences pmlmepriv causing
a null pointer deference if it is null.  Avoid this by also
calling rtw_free_mlme_priv_ie_data if the pointer is non-null.

Detected by CoverityScan, CID#1230262 ("Dereference before null check")
Fixes: 7b464c9fa5cc ("staging: r8188eu: Add files for new driver - part 4")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/staging/rtl8188eu/core/rtw_mlme.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/rtl8188eu/core/rtw_mlme.c b/drivers/staging/rtl8188eu/core/rtw_mlme.c
index b15cf17f77c5..74cf99e1b732 100644
--- a/drivers/staging/rtl8188eu/core/rtw_mlme.c
+++ b/drivers/staging/rtl8188eu/core/rtw_mlme.c
@@ -106,10 +106,10 @@ 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)
+	if (pmlmepriv) {
+		rtw_free_mlme_priv_ie_data(pmlmepriv);
 		vfree(pmlmepriv->free_bss_buf);
+	}
 }
 
 struct wlan_network *_rtw_alloc_network(struct mlme_priv *pmlmepriv)
-- 
2.14.1