[PATCH v3] Bluetooth: hci_event: Fix OOB read and infinite loop in hci_le_create_big_complete_evt

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

hci_le_create_big_complete_evt() iterates over BT_BOUND connections for
a BIG handle using a while loop, accessing ev->bis_handle[i++] on each
iteration.  However, there is no check that i stays within ev->num_bis
before the array access.

When a controller sends a LE_Create_BIG_Complete event with fewer
bis_handle entries than there are BT_BOUND connections for that BIG,
or with num_bis=0, the loop reads beyond the valid bis_handle[] flex
array into adjacent heap memory.  Since the out-of-bounds values
typically exceed HCI_CONN_HANDLE_MAX (0x0EFF), hci_conn_set_handle()
rejects them and the connection remains in BT_BOUND state.  The same
connection is then found again by hci_conn_hash_lookup_big_state(),
creating an infinite loop with hci_dev_lock held.

Fix this by terminating the BIG if in case not all BIS could be setup
properly.

Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Cc: stable@vger.kernel.org
Signed-off-by: ZhiTao Ou <hkbinbinbin@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/hci_event.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index b2ee6b6a0f56..3661ec0eab62 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7118,9 +7118,29 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
 			continue;
 		}
 
+		if (ev->num_bis <= i) {
+			bt_dev_err(hdev,
+				   "Not enough BIS handles for BIG 0x%2.2x",
+				   ev->handle);
+			ev->status = HCI_ERROR_UNSPECIFIED;
+			hci_connect_cfm(conn, ev->status);
+			hci_conn_del(conn);
+			break;
+		}
+
 		if (hci_conn_set_handle(conn,
-					__le16_to_cpu(ev->bis_handle[i++])))
+					__le16_to_cpu(ev->bis_handle[i++]))) {
+			bt_dev_err(hdev,
+				   "Failed to set BIS handle for BIG 0x%2.2x",
+				   ev->handle);
+			/* Force error so BIG gets terminated as not all BIS
+			 * could be connected.
+			 */
+			ev->status = HCI_ERROR_UNSPECIFIED;
+			hci_connect_cfm(conn, ev->status);
+			hci_conn_del(conn);
 			continue;
+		}
 
 		conn->state = BT_CONNECTED;
 		set_bit(HCI_CONN_BIG_CREATED, &conn->flags);
-- 
2.53.0