Commit a239110e authored Sep 30, 2023 by Pauli Virtanen Committed by Luiz Augusto von Dentz Oct 11, 2023

Bluetooth: hci_sync: always check if connection is alive before deleting



In hci_abort_conn_sync it is possible that conn is deleted concurrently
by something else, also e.g. when waiting for hdev->lock.  This causes
double deletion of the conn, so UAF or conn_hash.list corruption.

Fix by having all code paths check that the connection is still in
conn_hash before deleting it, while holding hdev->lock which prevents
any races.

Log (when powering off while BAP streaming, occurs rarely):
=======================================================================
kernel BUG at lib/list_debug.c:56!
...
 ? __list_del_entry_valid (lib/list_debug.c:56)
 hci_conn_del (net/bluetooth/hci_conn.c:154) bluetooth
 hci_abort_conn_sync (net/bluetooth/hci_sync.c:5415) bluetooth
 ? __pfx_hci_abort_conn_sync+0x10/0x10 [bluetooth]
 ? lock_release+0x1d5/0x3c0
 ? hci_disconnect_all_sync.constprop.0+0xb2/0x230 [bluetooth]
 ? __pfx_lock_release+0x10/0x10
 ? __kmem_cache_free+0x14d/0x2e0
 hci_disconnect_all_sync.constprop.0+0xda/0x230 [bluetooth]
 ? __pfx_hci_disconnect_all_sync.constprop.0+0x10/0x10 [bluetooth]
 ? hci_clear_adv_sync+0x14f/0x170 [bluetooth]
 ? __pfx_set_powered_sync+0x10/0x10 [bluetooth]
 hci_set_powered_sync+0x293/0x450 [bluetooth]
=======================================================================

Fixes: 94d9ba9f ("Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

parent 1ffc6f8c

net/bluetooth/hci_sync.c

+12 −14

Original line number	Diff line number	Diff line
		@@ -5369,6 +5369,7 @@ int hci_abort_conn_sync(struct hci_dev hdev, struct hci_conn conn, u8 reason)
		{
		int err = 0;
		u16 handle = conn->handle;
		bool disconnect = false;
		struct hci_conn *c;

		switch (conn->state) {
		@@ -5399,24 +5400,15 @@ int hci_abort_conn_sync(struct hci_dev hdev, struct hci_conn conn, u8 reason)
		hci_dev_unlock(hdev);
		return 0;
		case BT_BOUND:
		hci_dev_lock(hdev);
		hci_conn_failed(conn, reason);
		hci_dev_unlock(hdev);
		return 0;
		break;
		default:
		hci_dev_lock(hdev);
		conn->state = BT_CLOSED;
		hci_disconn_cfm(conn, reason);
		hci_conn_del(conn);
		hci_dev_unlock(hdev);
		return 0;
		disconnect = true;
		break;
		}

		hci_dev_lock(hdev);

		/* Check if the connection hasn't been cleanup while waiting
		* commands to complete.
		*/
		/* Check if the connection has been cleaned up concurrently */
		c = hci_conn_hash_lookup_handle(hdev, handle);
		if (!c \|\| c != conn) {
		err = 0;
		@@ -5428,7 +5420,13 @@ int hci_abort_conn_sync(struct hci_dev hdev, struct hci_conn conn, u8 reason)
		* or in case of LE it was still scanning so it can be cleanup
		* safely.
		*/
		if (disconnect) {
		conn->state = BT_CLOSED;
		hci_disconn_cfm(conn, reason);
		hci_conn_del(conn);
		} else {
		hci_conn_failed(conn, reason);
		}

		unlock:
		hci_dev_unlock(hdev);