mac80211: fix deadlock in driver-managed RX BA session start

commit bde59c475e0883e4c4294bcd9b9c7e08ae18c828 upstream.

When an RX BA session is started by the driver, and it has to tell
mac80211 about it, the corresponding bit in tid_rx_manage_offl gets
set and the BA session work is scheduled. Upon testing this bit, it
will call __ieee80211_start_rx_ba_session(), thus deadlocking as it
already holds the ampdu_mlme.mtx, which that acquires again.

Fix this by adding ___ieee80211_start_rx_ba_session(), a version of
the function that requires the mutex already held.

Fixes: 699cb58c8a52 ("mac80211: manage RX BA session offload without SKB queue")
Reported-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 28 insertions, 14 deletions

diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c
index 2b36eff5d97e..2849a1fc41c5 100644
--- a/net/mac80211/agg-rx.c
+++ b/net/mac80211/agg-rx.c
@@ -245,10 +245,10 @@ static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *d
 	ieee80211_tx_skb(sdata, skb);
 }
 
-void __ieee80211_start_rx_ba_session(struct sta_info *sta,
-				     u8 dialog_token, u16 timeout,
-				     u16 start_seq_num, u16 ba_policy, u16 tid,
-				     u16 buf_size, bool tx, bool auto_seq)
+void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
+				      u8 dialog_token, u16 timeout,
+				      u16 start_seq_num, u16 ba_policy, u16 tid,
+				      u16 buf_size, bool tx, bool auto_seq)
 {
 	struct ieee80211_local *local = sta->sdata->local;
 	struct tid_ampdu_rx *tid_agg_rx;
@@ -267,7 +267,7 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 		ht_dbg(sta->sdata,
 		       "STA %pM requests BA session on unsupported tid %d\n",
 		       sta->sta.addr, tid);
-		goto end_no_lock;
+		goto end;
 	}
 
 	if (!sta->sta.ht_cap.ht_supported) {
@@ -275,14 +275,14 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 		       "STA %pM erroneously requests BA session on tid %d w/o QoS\n",
 		       sta->sta.addr, tid);
 		/* send a response anyway, it's an error case if we get here */
-		goto end_no_lock;
+		goto end;
 	}
 
 	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
 		ht_dbg(sta->sdata,
 		       "Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
 		       sta->sta.addr, tid);
-		goto end_no_lock;
+		goto end;
 	}
 
 	/* sanity check for incoming parameters:
@@ -296,7 +296,7 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 		ht_dbg_ratelimited(sta->sdata,
 				   "AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n",
 				   sta->sta.addr, tid, ba_policy, buf_size);
-		goto end_no_lock;
+		goto end;
 	}
 	/* determine default buffer size */
 	if (buf_size == 0)
@@ -311,7 +311,7 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 	       buf_size, sta->sta.addr);
 
 	/* examine state machine */
-	mutex_lock(&sta->ampdu_mlme.mtx);
+	lockdep_assert_held(&sta->ampdu_mlme.mtx);
 
 	if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) {
 		if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
@@ -415,15 +415,25 @@ end:
 		__clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
 		sta->ampdu_mlme.tid_rx_token[tid] = dialog_token;
 	}
-	mutex_unlock(&sta->ampdu_mlme.mtx);
 
-end_no_lock:
 	if (tx)
 		ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
 					  dialog_token, status, 1, buf_size,
 					  timeout);
 }
 
+void __ieee80211_start_rx_ba_session(struct sta_info *sta,
+				     u8 dialog_token, u16 timeout,
+				     u16 start_seq_num, u16 ba_policy, u16 tid,
+				     u16 buf_size, bool tx, bool auto_seq)
+{
+	mutex_lock(&sta->ampdu_mlme.mtx);
+	___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
+					 start_seq_num, ba_policy, tid,
+					 buf_size, tx, auto_seq);
+	mutex_unlock(&sta->ampdu_mlme.mtx);
+}
+
 void ieee80211_process_addba_request(struct ieee80211_local *local,
 				     struct sta_info *sta,
 				     struct ieee80211_mgmt *mgmt,
diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c
index c92df492e898..198b2d3e56fd 100644
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -333,9 +333,9 @@ void ieee80211_ba_session_work(struct work_struct *work)
 
 		if (test_and_clear_bit(tid,
 				       sta->ampdu_mlme.tid_rx_manage_offl))
-			__ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid,
-							IEEE80211_MAX_AMPDU_BUF,
-							false, true);
+			___ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid,
+							 IEEE80211_MAX_AMPDU_BUF,
+							 false, true);
 
 		if (test_and_clear_bit(tid + IEEE80211_NUM_TIDS,
 				       sta->ampdu_mlme.tid_rx_manage_offl))
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 2197c62a0a6e..9675814f64db 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1760,6 +1760,10 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 				     u8 dialog_token, u16 timeout,
 				     u16 start_seq_num, u16 ba_policy, u16 tid,
 				     u16 buf_size, bool tx, bool auto_seq);
+void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
+				      u8 dialog_token, u16 timeout,
+				      u16 start_seq_num, u16 ba_policy, u16 tid,
+				      u16 buf_size, bool tx, bool auto_seq);
 void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
 					 enum ieee80211_agg_stop_reason reason);
 void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,