staging: rtl8192u: Fix use after free in ieee80211_rx()

[ Upstream commit bcc5e2dcf09089b337b76fc1a589f6ff95ca19ac ]

We cannot dereference the "skb" pointer after calling
ieee80211_monitor_rx(), because it is a use after free.

Fixes: 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/Y33BArx3k/aw6yv/@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c b/drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c
index b58e759..3686b3c 100644 (file)
--- a/drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c
+++ b/drivers/staging/rtl8192u/ieee80211/ieee80211_rx.c
@@ -951,9 +951,11 @@ int ieee80211_rx(struct ieee80211_device *ieee, struct sk_buff *skb,
 #endif
 
        if (ieee->iw_mode == IW_MODE_MONITOR) {
+               unsigned int len = skb->len;
+
                ieee80211_monitor_rx(ieee, skb, rx_stats);
                stats->rx_packets++;
-               stats->rx_bytes += skb->len;
+               stats->rx_bytes += len;
                return 1;
        }