From: Johannes Berg Date: Fri, 24 Sep 2010 09:20:47 +0000 (+0200) Subject: mac80211: fix use-after-free X-Git-Tag: v2.6.33.8~470 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3f10d217f3744132e9f896d7d4b5cedf7ee2e821;p=karo-tx-linux.git mac80211: fix use-after-free commit cd87a2d3a33d75a646f1aa1aa2ee5bf712d6f963 upstream. commit 8c0c709eea5cbab97fb464cd68b06f24acc58ee1 Author: Johannes Berg Date: Wed Nov 25 17:46:15 2009 +0100 mac80211: move cmntr flag out of rx flags moved the CMTR flag into the skb's status, and in doing so introduced a use-after-free -- when the skb has been handed to cooked monitors the status setting will touch now invalid memory. Additionally, moving it there has effectively discarded the optimisation -- since the bit is only ever set on freed SKBs, and those were a copy, it could never be checked. For the current release, fixing this properly is a bit too involved, so let's just remove the problematic code and leave userspace with one copy of each frame for each virtual interface. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 701e63a609f6..d1625993fa58 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -2123,9 +2123,6 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx, struct net_device *prev_dev = NULL; struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); - if (status->flag & RX_FLAG_INTERNAL_CMTR) - goto out_free_skb; - if (skb_headroom(skb) < sizeof(*rthdr) && pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) goto out_free_skb; @@ -2184,7 +2181,6 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx, } else goto out_free_skb; - status->flag |= RX_FLAG_INTERNAL_CMTR; return; out_free_skb: