[PATCH 3.2 38/94] mac80211_hwsim: Add missing check for HWSIM_ATTR_SIGNAL

[Ben Hutchings]

3.2.82-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Willi <martin@xxxxxxxxxxxxxx>

commit 62397da50bb20a6b812c949ef465d7e69fe54bb6 upstream.

A wmediumd that does not send this attribute causes a NULL pointer
dereference, as the attribute is accessed even if it does not exist.

The attribute was required but never checked ever since userspace frame
forwarding has been introduced. The issue gets more problematic once we
allow wmediumd registration from user namespaces.

Fixes: 7882513bacb1 ("mac80211_hwsim driver support userspace frame tx/rx")
Signed-off-by: Martin Willi <martin@xxxxxxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
[bwh: Backported to 3.2: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/mac80211_hwsim.c | 1 +
 1 file changed, 1 insertion(+)

--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -1440,6 +1440,7 @@ static int hwsim_tx_info_frame_received_
 	if (!info->attrs[HWSIM_ATTR_ADDR_TRANSMITTER] ||
 	   !info->attrs[HWSIM_ATTR_FLAGS] ||
 	   !info->attrs[HWSIM_ATTR_COOKIE] ||
+	   !info->attrs[HWSIM_ATTR_SIGNAL] ||
 	   !info->attrs[HWSIM_ATTR_TX_INFO])
 		goto out;