mac80211: fix use-after-free
commit 8c0c709eea5cbab97fb464cd68b06f24acc58ee1
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>
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index fa0f37e..28624282 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -2199,9 +2199,6 @@
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 @@
} else
goto out_free_skb;
- status->flag |= RX_FLAG_INTERNAL_CMTR;
return;
out_free_skb: