Bluetooth: hci_event: validate skb length for unknown CC opcode

In hci_cmd_complete_evt(), if the command complete event has an unknown
opcode, we assume the first byte of the remaining skb->data contains the
return status. However, parameter data has previously been pulled in
hci_event_func(), which may leave the skb empty. If so, using skb->data[0]
for the return status uses un-init memory.

The fix is to check skb->len before using skb->data.

Reported-by: syzbot+a9a4bedfca6aa9d7fa24@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=a9a4bedfca6aa9d7fa24
Tested-by: syzbot+a9a4bedfca6aa9d7fa24@syzkaller.appspotmail.com
Fixes: afcb3369f46ed ("Bluetooth: hci_event: Fix vendor (unknown) opcode status handling")
Signed-off-by: Raphael Pinsonneault-Thibeault <rpthibeault@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index d37db364acf7403c00ff61573887c5efe23ecec6..f20c826509b6fe0d52375bae4e6b17459981fff6 100644 (file)
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4218,6 +4218,13 @@ static void hci_cmd_complete_evt(struct hci_dev *hdev, void *data,
        }
 
        if (i == ARRAY_SIZE(hci_cc_table)) {
+               if (!skb->len) {
+                       bt_dev_err(hdev, "Unexpected cc 0x%4.4x with no status",
+                                  *opcode);
+                       *status = HCI_ERROR_UNSPECIFIED;
+                       return;
+               }
+
                /* Unknown opcode, assume byte 0 contains the status, so
                 * that e.g. __hci_cmd_sync() properly returns errors
                 * for vendor specific commands send by HCI drivers.