[PATCH v2] staging: rtl8723au: fix potential leak in update_bcn_wps_ie()

[Christian Engelmayer]

Fix a potential leak in the error path of function update_bcn_wps_ie().
Move the affected input verification to the beginning of the function so
that it may return directly without leaking already allocated memory.
Detected by Coverity - CID 1077718.

Signed-off-by: Christian Engelmayer <cengelma@xxxxxx>
---
v2: Added change suggested by Mateusz Guzik:

    Move the check before allocating the memory instead of freeing the
    resource afterwards in the error path.

Compile tested and applies against branch staging-next of tree
git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
---
 drivers/staging/rtl8723au/core/rtw_ap.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/rtl8723au/core/rtw_ap.c b/drivers/staging/rtl8723au/core/rtw_ap.c
index 9b31412..da028c535 100644
--- a/drivers/staging/rtl8723au/core/rtw_ap.c
+++ b/drivers/staging/rtl8723au/core/rtw_ap.c
@@ -1256,6 +1256,10 @@ static void update_bcn_wps_ie(struct rtw_adapter *padapter)
 
 	DBG_8723A("%s\n", __func__);
 
+	pwps_ie_src = pmlmepriv->wps_beacon_ie;
+	if (pwps_ie_src == NULL)
+		return;
+
 	pwps_ie = rtw_get_wps_ie23a(ie+_FIXED_IE_LENGTH_, ielen-_FIXED_IE_LENGTH_, NULL, &wps_ielen);
 
 	if (pwps_ie == NULL || wps_ielen == 0)
@@ -1274,10 +1278,6 @@ static void update_bcn_wps_ie(struct rtw_adapter *padapter)
 			       remainder_ielen);
 	}
 
-	pwps_ie_src = pmlmepriv->wps_beacon_ie;
-	if (pwps_ie_src == NULL)
-		return;
-
 	wps_ielen = (uint)pwps_ie_src[1];/* to get ie data len */
 	if ((wps_offset+wps_ielen+2+remainder_ielen)<= MAX_IE_SZ)
 	{
-- 
1.9.1

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