2022-01-13 13:40:09

by Soenke Huster

[permalink] [raw]
Subject: [PATCH] Bluetooth: fix null ptr deref on hci_sync_conn_complete_evt

This event is specified just for SCO and eSCO link types.
On the reception of a HCI_Synchronous_Connection_Complete for a BDADDR
of an existing LE connection, LE link type and a status that triggers the
second case of the packet processing a NULL pointer dereference happens,
as conn->link is NULL.

Signed-off-by: Soenke Huster <[email protected]>
I found this null pointer dereference while fuzzing bluetooth-next.
On the described behaviour, a null ptr deref in line 4723 happens, as
conn->link is NULL. According to the Core spec, Link_Type must be SCO or eSCO,
all other values are reserved for future use. Checking that mitigates a null
pointer dereference.

net/bluetooth/hci_event.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index fc30f4c03d29..fc3f29d195d2 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4661,6 +4661,11 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev, void *data,
struct hci_ev_sync_conn_complete *ev = data;
struct hci_conn *conn;

+ if (ev->link_type != SCO_LINK || ev->link_type != ESCO_LINK) {
+ bt_dev_err(hdev, "Ignoring connect complete event for invalid link type");
+ return;
+ }
bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);