[PATCH v4] Bluetooth: hci_event: Fix OOB read and infinite loop in hci_le_create_big_complete_evt

Luiz Augusto von Dentz
2026-04-13T19:32:23Z

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 | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index b2ee6b6a0f56..cd4160f741b4 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);
@@ -7129,7 +7149,10 @@ static void hci_le_create_big_complete_evt(struct hci_dev *hdev, void *data,
hci_iso_setup_path(conn);
}

- if (!ev->status && !i)
+ /* If there is an unexpected error or if no BISes have been connected
+ * for the BIG, terminate it.
+ */
+ if (ev->status == HCI_ERROR_UNSPECIFIED || (!ev->status && !i))
/* If no BISes have been connected for the BIG,
* terminate. This is in case all bound connections
* have been closed before the BIG creation
--
2.53.0