From d12c74528e3065c90df70fbc06ec6ffd6e804738 Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Fri, 8 Oct 2010 22:27:07 +0200 Subject: [PATCH] mac80211: fix possible null-pointer de-reference This patch not only fixes a null-pointer de-reference that would be triggered by a PLINK_OPEN frame with mis- matching/incompatible mesh configuration, but also responds correctly to non-compatible PLINK_OPEN frames by generating a PLINK_CLOSE with the right reason code. The original bug was detected by smatch. ( http://repo.or.cz/w/smatch.git ) net/mac80211/mesh_plink.c +574 mesh_rx_plink_frame(168) error: we previously assumed 'sta' could be null. Cc: Reviewed-and-Tested-by: Steve deRosier Reviewed-and-Tested-by: Javier Cardona Acked-by: Johannes Berg Signed-off-by: Christian Lamparter Signed-off-by: John W. Linville --- net/mac80211/mesh_plink.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c index ea13a80a476c..1c91f0f3c307 100644 --- a/net/mac80211/mesh_plink.c +++ b/net/mac80211/mesh_plink.c @@ -412,7 +412,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m enum plink_event event; enum plink_frame_type ftype; size_t baselen; - bool deactivated; + bool deactivated, matches_local = true; u8 ie_len; u8 *baseaddr; __le16 plid, llid, reason; @@ -487,6 +487,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m /* Now we will figure out the appropriate event... */ event = PLINK_UNDEFINED; if (ftype != PLINK_CLOSE && (!mesh_matches_local(&elems, sdata))) { + matches_local = false; switch (ftype) { case PLINK_OPEN: event = OPN_RJCT; @@ -498,7 +499,15 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m /* avoid warning */ break; } - spin_lock_bh(&sta->lock); + } + + if (!sta && !matches_local) { + rcu_read_unlock(); + reason = cpu_to_le16(MESH_CAPABILITY_POLICY_VIOLATION); + llid = 0; + mesh_plink_frame_tx(sdata, PLINK_CLOSE, mgmt->sa, llid, + plid, reason); + return; } else if (!sta) { /* ftype == PLINK_OPEN */ u32 rates; @@ -522,7 +531,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m } event = OPN_ACPT; spin_lock_bh(&sta->lock); - } else { + } else if (matches_local) { spin_lock_bh(&sta->lock); switch (ftype) { case PLINK_OPEN: @@ -564,6 +573,8 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m rcu_read_unlock(); return; } + } else { + spin_lock_bh(&sta->lock); } mpl_dbg("Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n", -- 2.20.1