CVE-2026-64404 Bluetooth: ISO: avoid NULL deref of conn in iso_conn_big_sync()

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: avoid NULL deref of conn in isoconnbigsync isoconnbigsync drops the socket lock to call hcigetroute and then re-acquires it, but dereferences isopisk-conn-hcon afterwards without re-checking that conn is still...