Merge tag 'for-net-2023-05-19' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth

Luiz Augusto von Dentz says:

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

 - Fix compiler warnings on btnxpuart
 - Fix potential double free on hci_conn_unlink
 - Fix UAF on hci_conn_hash_flush

* tag 'for-net-2023-05-19' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth:
  Bluetooth: btnxpuart: Fix compiler warnings
  Bluetooth: Unlink CISes when LE disconnects in hci_conn_del
  Bluetooth: Fix UAF in hci_conn_hash_flush again
  Bluetooth: Refcnt drop must be placed last in hci_conn_unlink
  Bluetooth: Fix potential double free caused by hci_conn_unlink
====================

Link: https://lore.kernel.org/r/20230519233056.2024340-1-luiz.dentz@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 45 insertions, 40 deletions

diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
index 3a34d7c1475bce..52ef44688d38a3 100644
--- a/drivers/bluetooth/btnxpuart.c
+++ b/drivers/bluetooth/btnxpuart.c
@@ -1319,17 +1319,17 @@ static void nxp_serdev_remove(struct serdev_device *serdev)
 	hci_free_dev(hdev);
 }
 
-static struct btnxpuart_data w8987_data = {
+static struct btnxpuart_data w8987_data __maybe_unused = {
 	.helper_fw_name = NULL,
 	.fw_name = FIRMWARE_W8987,
 };
 
-static struct btnxpuart_data w8997_data = {
+static struct btnxpuart_data w8997_data __maybe_unused = {
 	.helper_fw_name = FIRMWARE_HELPER,
 	.fw_name = FIRMWARE_W8997,
 };
 
-static const struct of_device_id nxpuart_of_match_table[] = {
+static const struct of_device_id nxpuart_of_match_table[] __maybe_unused = {
 	{ .compatible = "nxp,88w8987-bt", .data = &w8987_data },
 	{ .compatible = "nxp,88w8997-bt", .data = &w8997_data },
 	{ }
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index a6c8aee2f256c6..8baf346399397e 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1327,7 +1327,7 @@ int hci_le_create_cis(struct hci_conn *conn);
 
 struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
 			      u8 role);
-int hci_conn_del(struct hci_conn *conn);
+void hci_conn_del(struct hci_conn *conn);
 void hci_conn_hash_flush(struct hci_dev *hdev);
 void hci_conn_check_pending(struct hci_dev *hdev);
 
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 640b951bf40a11..f75ef12f18f774 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1083,8 +1083,28 @@ static void hci_conn_unlink(struct hci_conn *conn)
 	if (!conn->parent) {
 		struct hci_link *link, *t;
 
-		list_for_each_entry_safe(link, t, &conn->link_list, list)
-			hci_conn_unlink(link->conn);
+		list_for_each_entry_safe(link, t, &conn->link_list, list) {
+			struct hci_conn *child = link->conn;
+
+			hci_conn_unlink(child);
+
+			/* If hdev is down it means
+			 * hci_dev_close_sync/hci_conn_hash_flush is in progress
+			 * and links don't need to be cleanup as all connections
+			 * would be cleanup.
+			 */
+			if (!test_bit(HCI_UP, &hdev->flags))
+				continue;
+
+			/* Due to race, SCO connection might be not established
+			 * yet at this point. Delete it now, otherwise it is
+			 * possible for it to be stuck and can't be deleted.
+			 */
+			if ((child->type == SCO_LINK ||
+			     child->type == ESCO_LINK) &&
+			    child->handle == HCI_CONN_HANDLE_UNSET)
+				hci_conn_del(child);
+		}
 
 		return;
 	}
@@ -1092,35 +1112,30 @@ static void hci_conn_unlink(struct hci_conn *conn)
 	if (!conn->link)
 		return;
 
-	hci_conn_put(conn->parent);
-	conn->parent = NULL;
-
 	list_del_rcu(&conn->link->list);
 	synchronize_rcu();
 
+	hci_conn_drop(conn->parent);
+	hci_conn_put(conn->parent);
+	conn->parent = NULL;
+
 	kfree(conn->link);
 	conn->link = NULL;
-
-	/* Due to race, SCO connection might be not established
-	 * yet at this point. Delete it now, otherwise it is
-	 * possible for it to be stuck and can't be deleted.
-	 */
-	if (conn->handle == HCI_CONN_HANDLE_UNSET)
-		hci_conn_del(conn);
 }
 
-int hci_conn_del(struct hci_conn *conn)
+void hci_conn_del(struct hci_conn *conn)
 {
 	struct hci_dev *hdev = conn->hdev;
 
 	BT_DBG("%s hcon %p handle %d", hdev->name, conn, conn->handle);
 
+	hci_conn_unlink(conn);
+
 	cancel_delayed_work_sync(&conn->disc_work);
 	cancel_delayed_work_sync(&conn->auto_accept_work);
 	cancel_delayed_work_sync(&conn->idle_work);
 
 	if (conn->type == ACL_LINK) {
-		hci_conn_unlink(conn);
 		/* Unacked frames */
 		hdev->acl_cnt += conn->sent;
 	} else if (conn->type == LE_LINK) {
@@ -1131,13 +1146,6 @@ int hci_conn_del(struct hci_conn *conn)
 		else
 			hdev->acl_cnt += conn->sent;
 	} else {
-		struct hci_conn *acl = conn->parent;
-
-		if (acl) {
-			hci_conn_unlink(conn);
-			hci_conn_drop(acl);
-		}
-
 		/* Unacked ISO frames */
 		if (conn->type == ISO_LINK) {
 			if (hdev->iso_pkts)
@@ -1160,8 +1168,6 @@ int hci_conn_del(struct hci_conn *conn)
 	 * rest of hci_conn_del.
 	 */
 	hci_conn_cleanup(conn);
-
-	return 0;
 }
 
 struct hci_dev *hci_get_route(bdaddr_t *dst, bdaddr_t *src, uint8_t src_type)
@@ -2462,22 +2468,21 @@ timer:
 /* Drop all connection on the device */
 void hci_conn_hash_flush(struct hci_dev *hdev)
 {
-	struct hci_conn_hash *h = &hdev->conn_hash;
-	struct hci_conn *c, *n;
+	struct list_head *head = &hdev->conn_hash.list;
+	struct hci_conn *conn;
 
 	BT_DBG("hdev %s", hdev->name);
 
-	list_for_each_entry_safe(c, n, &h->list, list) {
-		c->state = BT_CLOSED;
-
-		hci_disconn_cfm(c, HCI_ERROR_LOCAL_HOST_TERM);
-
-		/* Unlink before deleting otherwise it is possible that
-		 * hci_conn_del removes the link which may cause the list to
-		 * contain items already freed.
-		 */
-		hci_conn_unlink(c);
-		hci_conn_del(c);
+	/* We should not traverse the list here, because hci_conn_del
+	 * can remove extra links, which may cause the list traversal
+	 * to hit items that have already been released.
+	 */
+	while ((conn = list_first_entry_or_null(head,
+						struct hci_conn,
+						list)) != NULL) {
+		conn->state = BT_CLOSED;
+		hci_disconn_cfm(conn, HCI_ERROR_LOCAL_HOST_TERM);
+		hci_conn_del(conn);
 	}
 }