forked from Minki/linux
mac80211: fix use-after-free
commit 8c0c709eea
Author: Johannes Berg <johannes@sipsolutions.net>
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 <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -2199,9 +2199,6 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
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struct net_device *prev_dev = NULL;
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struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
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if (status->flag & RX_FLAG_INTERNAL_CMTR)
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goto out_free_skb;
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if (skb_headroom(skb) < sizeof(*rthdr) &&
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pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC))
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goto out_free_skb;
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@ -2260,7 +2257,6 @@ static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
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} else
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goto out_free_skb;
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status->flag |= RX_FLAG_INTERNAL_CMTR;
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return;
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out_free_skb:
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