mac80211: fix tid_agg_rx NULL dereference

commit 1c3d185a9a0b136a58e73b02912d593d0303d1da upstream.

On drivers setting the SUPPORTS_REORDERING_BUFFER hardware flag,
we crash when the peer sends an AddBA request while we already
have a session open on the seame TID; this is because on those
drivers, the tid_agg_rx is left NULL even though the session is
valid, and the agg_session_valid bit is set.

To fix this, store the dialog tokens outside the tid_agg_rx to
be able to compare them to the received AddBA request.

Fixes: f89e07d4cf26 ("mac80211: agg-rx: refuse ADDBA Request with timeout update")
Reported-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index a2fcdb4..14ec63a 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -205,7 +205,7 @@
 		p += scnprintf(p, sizeof(buf) + buf - p, "%02d", i);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t\t%x", !!tid_rx);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.2x",
-				tid_rx ? tid_rx->dialog_token : 0);
+				tid_rx ? sta->ampdu_mlme.tid_rx_token[i] : 0);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.3x",
 				tid_rx ? tid_rx->ssn : 0);