linux-kernel - [PATCH] cfg80211: fix wext-compat memory leak

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Date:   Sun, 30 Sep 2018 12:53:00 +0200
From:   stefan.seyfried@...glemail.com
To:     linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org
Cc:     Stefan Seyfried <seife+kernel@...systems.com>
Subject: [PATCH] cfg80211: fix wext-compat memory leak

From: Stefan Seyfried <seife+kernel@...systems.com>

cfg80211_wext_giwrate and sinfo.pertid might allocate sinfo.pertid via
rdev_get_station(), but never release it

Signed-off-by: Stefan Seyfried <seife+kernel@...systems.com>
---
 net/wireless/wext-compat.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
index 167f7025ac98..f462336aac1c 100644
--- a/net/wireless/wext-compat.c
+++ b/net/wireless/wext-compat.c
@@ -1277,12 +1277,16 @@ static int cfg80211_wext_giwrate(struct net_device *dev,
 	err = rdev_get_station(rdev, dev, addr, &sinfo);
 	if (err)
 		return err;
-
 	if (!(sinfo.filled & BIT_ULL(NL80211_STA_INFO_TX_BITRATE)))
 		return -EOPNOTSUPP;
 
 	rate->value = 100000 * cfg80211_calculate_bitrate(&sinfo.txrate);
 
+	/* sta_set_sinfo(), called from ieee80211_get_station(), called from
+	 * rdev_get_station via rdev->ops->get_station, allocates pertid struct
+	 * which we do not use here. */
+	kfree(sinfo.pertid);
+
 	return 0;
 }
 
@@ -1293,7 +1297,7 @@ static struct iw_statistics *cfg80211_wireless_stats(struct net_device *dev)
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 	/* we are under RTNL - globally locked - so can use static structs */
 	static struct iw_statistics wstats;
-	static struct station_info sinfo;
+	static struct station_info sinfo = {};
 	u8 bssid[ETH_ALEN];
 
 	if (dev->ieee80211_ptr->iftype != NL80211_IFTYPE_STATION)
@@ -1352,6 +1356,9 @@ static struct iw_statistics *cfg80211_wireless_stats(struct net_device *dev)
 	if (sinfo.filled & BIT_ULL(NL80211_STA_INFO_TX_FAILED))
 		wstats.discard.retries = sinfo.tx_failed;
 
+	/* see cfg80211_wext_giwrate() above */
+	kfree(sinfo.pertid);
+
 	return &wstats;
 }
 
-- 
2.19.0