From cd87a2d3a33d75a646f1aa1aa2ee5bf712d6f963 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 24 Sep 2010 11:20:47 +0200 Subject: [PATCH] mac80211: fix use-after-free 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. Cc: stable@kernel.org [2.6.33+] Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/rx.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index fa0f37e4afe4..28624282c5f3 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -2199,9 +2199,6 @@ 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; @@ -2260,7 +2257,6 @@ 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: