Merge tag 'for-net-2022-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth

Luiz Augusto von Dentz says:

====================
bluetooth pull request for net:

 - Fix early wakeup after suspend
 - Fix double free on error
 - Fix use-after-free on l2cap_chan_put

* tag 'for-net-2022-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth:
  Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put
  Bluetooth: Always set event mask on suspend
  Bluetooth: mgmt: Fix double free on error path
====================

Link: https://lore.kernel.org/r/20220726221328.423714-1-luiz.dentz@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

include/net/bluetooth/l2cap.h

@@ -847,6 +847,7 @@ enum {
 };
 
 void l2cap_chan_hold(struct l2cap_chan *c);
+struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c);
 void l2cap_chan_put(struct l2cap_chan *c);
 
 static inline void l2cap_chan_lock(struct l2cap_chan *chan)

net/bluetooth/hci_sync.c

@@ -4973,6 +4973,9 @@ int hci_suspend_sync(struct hci_dev *hdev)
 		return err;
 	}
 
+	/* Update event mask so only the allowed event can wakeup the host */
+	hci_set_event_mask_sync(hdev);
+
 	/* Only configure accept list if disconnect succeeded and wake
 	 * isn't being prevented.
 	 */
@@ -4984,9 +4987,6 @@ int hci_suspend_sync(struct hci_dev *hdev)
 	/* Unpause to take care of updating scanning params */
 	hdev->scanning_paused = false;
 
-	/* Update event mask so only the allowed event can wakeup the host */
-	hci_set_event_mask_sync(hdev);
-
 	/* Enable event filter for paired devices */
 	hci_update_event_filter_sync(hdev);
 

net/bluetooth/l2cap_core.c

@@ -111,23 +111,28 @@ static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 }
 
 /* Find channel with given SCID.
- * Returns locked channel. */
+ * Returns a reference locked channel.
+ */
 static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 						 u16 cid)
 {
 	struct l2cap_chan *c;
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_scid(conn, cid);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
 }
 
 /* Find channel with given DCID.
- * Returns locked channel.
+ * Returns a reference locked channel.
  */
 static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 						 u16 cid)
@@ -136,8 +141,12 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_dcid(conn, cid);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
@@ -162,8 +171,12 @@ static struct l2cap_chan *l2cap_get_chan_by_ident(struct l2cap_conn *conn,
 
 	mutex_lock(&conn->chan_lock);
 	c = __l2cap_get_chan_by_ident(conn, ident);
-	if (c)
-		l2cap_chan_lock(c);
+	if (c) {
+		/* Only lock if chan reference is not 0 */
+		c = l2cap_chan_hold_unless_zero(c);
+		if (c)
+			l2cap_chan_lock(c);
+	}
 	mutex_unlock(&conn->chan_lock);
 
 	return c;
@@ -497,6 +510,16 @@ void l2cap_chan_hold(struct l2cap_chan *c)
 	kref_get(&c->kref);
 }
 
+struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c)
+{
+	BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref));
+
+	if (!kref_get_unless_zero(&c->kref))
+		return NULL;
+
+	return c;
+}
+
 void l2cap_chan_put(struct l2cap_chan *c)
 {
 	BT_DBG("chan %p orig refcnt %u", c, kref_read(&c->kref));
@@ -1968,7 +1991,10 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 			src_match = !bacmp(&c->src, src);
 			dst_match = !bacmp(&c->dst, dst);
 			if (src_match && dst_match) {
-				l2cap_chan_hold(c);
+				c = l2cap_chan_hold_unless_zero(c);
+				if (!c)
+					continue;
+
 				read_unlock(&chan_list_lock);
 				return c;
 			}
@@ -1983,7 +2009,7 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm,
 	}
 
 	if (c1)
-		l2cap_chan_hold(c1);
+		c1 = l2cap_chan_hold_unless_zero(c1);
 
 	read_unlock(&chan_list_lock);
 
@@ -4463,6 +4489,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 
 unlock:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 	return err;
 }
 
@@ -4577,6 +4604,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 
 done:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 	return err;
 }
 
@@ -5304,6 +5332,7 @@ static inline int l2cap_move_channel_req(struct l2cap_conn *conn,
 	l2cap_send_move_chan_rsp(chan, result);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5396,6 +5425,7 @@ static void l2cap_move_continue(struct l2cap_conn *conn, u16 icid, u16 result)
 	}
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid,
@@ -5425,6 +5455,7 @@ static void l2cap_move_fail(struct l2cap_conn *conn, u8 ident, u16 icid,
 	l2cap_send_move_chan_cfm(chan, L2CAP_MC_UNCONFIRMED);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static int l2cap_move_channel_rsp(struct l2cap_conn *conn,
@@ -5488,6 +5519,7 @@ static int l2cap_move_channel_confirm(struct l2cap_conn *conn,
 	l2cap_send_move_chan_cfm_rsp(conn, cmd->ident, icid);
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5523,6 +5555,7 @@ static inline int l2cap_move_channel_confirm_rsp(struct l2cap_conn *conn,
 	}
 
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -5895,12 +5928,11 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn,
 	if (credits > max_credits) {
 		BT_ERR("LE credits overflow");
 		l2cap_send_disconn_req(chan, ECONNRESET);
-		l2cap_chan_unlock(chan);
 
 		/* Return 0 so that we don't trigger an unnecessary
 		 * command reject packet.
 		 */
-		return 0;
+		goto unlock;
 	}
 
 	chan->tx_credits += credits;
@@ -5911,7 +5943,9 @@ static inline int l2cap_le_credits(struct l2cap_conn *conn,
 	if (chan->tx_credits)
 		chan->ops->resume(chan);
 
+unlock:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 	return 0;
 }
@@ -7597,6 +7631,7 @@ static void l2cap_data_channel(struct l2cap_conn *conn, u16 cid,
 
 done:
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 }
 
 static void l2cap_conless_channel(struct l2cap_conn *conn, __le16 psm,
@@ -8085,7 +8120,7 @@ static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c,
 		if (src_type != c->src_type)
 			continue;
 
-		l2cap_chan_hold(c);
+		c = l2cap_chan_hold_unless_zero(c);
 		read_unlock(&chan_list_lock);
 		return c;
 	}

net/bluetooth/mgmt.c

@@ -4723,7 +4723,6 @@ static int __add_adv_patterns_monitor(struct sock *sk, struct hci_dev *hdev,
 		else
 			status = MGMT_STATUS_FAILED;
 
-		mgmt_pending_remove(cmd);
 		goto unlock;
 	}