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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: <stable@kernel.org>
Reviewed-and-Tested-by: Steve deRosier <steve@cozybit.com>
Reviewed-and-Tested-by: Javier Cardona <javier@cozybit.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Christian Lamparter 2010-10-08 22:27:07 +02:00 committed by John W. Linville
parent 7109ca5c80
commit d12c74528e
1 changed files with 14 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
net/mac80211/mesh_plink.c
View File

@ -412,7 +412,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
enum plink_event event; enum plink_event event;
enum plink_frame_type ftype; enum plink_frame_type ftype;
size_t baselen; size_t baselen;
bool deactivated; bool deactivated, matches_local = true;
u8 ie_len; u8 ie_len;
u8 *baseaddr; u8 *baseaddr;
__le16 plid, llid, reason; __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... */ /* Now we will figure out the appropriate event... */
event = PLINK_UNDEFINED; event = PLINK_UNDEFINED;
if (ftype != PLINK_CLOSE && (!mesh_matches_local(&elems, sdata))) { if (ftype != PLINK_CLOSE && (!mesh_matches_local(&elems, sdata))) {
matches_local = false;
switch (ftype) { switch (ftype) {
case PLINK_OPEN: case PLINK_OPEN:
event = OPN_RJCT; event = OPN_RJCT;
@ -498,7 +499,15 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
/* avoid warning */ /* avoid warning */
break; 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) { } else if (!sta) {
/* ftype == PLINK_OPEN */ /* ftype == PLINK_OPEN */
u32 rates; u32 rates;
@ -522,7 +531,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
} }
event = OPN_ACPT; event = OPN_ACPT;
spin_lock_bh(&sta->lock); spin_lock_bh(&sta->lock);
} else { } else if (matches_local) {
spin_lock_bh(&sta->lock); spin_lock_bh(&sta->lock);
switch (ftype) { switch (ftype) {
case PLINK_OPEN: case PLINK_OPEN:
@ -564,6 +573,8 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
rcu_read_unlock(); rcu_read_unlock();
return; return;
} }
} else {
spin_lock_bh(&sta->lock);
} }
mpl_dbg("Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n", mpl_dbg("Mesh plink (peer, state, llid, plid, event): %pM %s %d %d %d\n",