netdev - [PATCH] cfg80211: fix error path in cfg80211_wext

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Date:	Wed, 23 Dec 2009 15:33:35 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	Dan Carpenter <error27@...il.com>
Cc:	"John W. Linville" <linville@...driver.com>,
	"David S. Miller" <davem@...emloft.net>,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH] cfg80211: fix error path in cfg80211_wext_siwscan

If there's an invalid channel or SSID, the code leaks
the scan request. Always free the scan request, unless
it was successfully given to the driver.

Reported-by: Dan Carpenter <error27@...il.com>
Signed-off-by: Johannes Berg <johannes@...solutions.net>
---
I kinda prefer this, thoughts?

 net/wireless/scan.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- wireless-testing.orig/net/wireless/scan.c	2009-12-23 15:27:20.000000000 +0100
+++ wireless-testing/net/wireless/scan.c	2009-12-23 15:32:52.000000000 +0100
@@ -601,7 +601,7 @@ int cfg80211_wext_siwscan(struct net_dev
 	struct cfg80211_registered_device *rdev;
 	struct wiphy *wiphy;
 	struct iw_scan_req *wreq = NULL;
-	struct cfg80211_scan_request *creq;
+	struct cfg80211_scan_request *creq = NULL;
 	int i, err, n_channels = 0;
 	enum ieee80211_band band;
 
@@ -694,8 +694,10 @@ int cfg80211_wext_siwscan(struct net_dev
 	/* translate "Scan for SSID" request */
 	if (wreq) {
 		if (wrqu->data.flags & IW_SCAN_THIS_ESSID) {
-			if (wreq->essid_len > IEEE80211_MAX_SSID_LEN)
-				return -EINVAL;
+			if (wreq->essid_len > IEEE80211_MAX_SSID_LEN) {
+				err = -EINVAL;
+				goto out;
+			}
 			memcpy(creq->ssids[0].ssid, wreq->essid, wreq->essid_len);
 			creq->ssids[0].ssid_len = wreq->essid_len;
 		}
@@ -707,12 +709,15 @@ int cfg80211_wext_siwscan(struct net_dev
 	err = rdev->ops->scan(wiphy, dev, creq);
 	if (err) {
 		rdev->scan_req = NULL;
-		kfree(creq);
+		/* creq will be freed below */
 	} else {
 		nl80211_send_scan_start(rdev, dev);
+		/* creq now owned by driver */
+		creq = NULL;
 		dev_hold(dev);
 	}
  out:
+	kfree(creq);
 	cfg80211_unlock_rdev(rdev);
 	return err;
 }


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