linux-kernel - [PATCH 3.16 048/136] staging: rtl8188eu: avoid a null dereference on pmlmepriv

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Message-ID: <lsq.1518323471.46040531@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Colin Ian King" <colin.king@...onical.com>
Subject: [PATCH 3.16 048/136] staging: rtl8188eu: avoid a null dereference
 on pmlmepriv

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

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

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

commit 123c0aab0050cd0e07ce18e453389fbbb0a5a425 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/staging/rtl8188eu/core/rtw_mlme.c
+++ b/drivers/staging/rtl8188eu/core/rtw_mlme.c
@@ -120,9 +120,8 @@ void rtw_free_mlme_priv_ie_data(struct m
 
 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);
 	}