CVE-2026-64404

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: ISO: avoid NULL deref of conn in iso_conn_big_sync()

iso_conn_big_sync() drops the socket lock to call hci_get_route() and

then re-acquires it, but dereferences iso_pi(sk)->conn->hcon afterwards

without re-checking that conn is still valid.

While the lock is dropped, the connection can be torn down under the

same socket lock: iso_disconn_cfm() -> iso_conn_del() -> iso_chan_del()

sets iso_pi(sk)->conn to NULL (and the broadcast teardown path can also

clear conn->hcon on its own). When iso_conn_big_sync() re-acquires the

lock and reads conn->hcon, conn may be NULL, causing a NULL pointer

dereference (hcon is the first member of struct iso_conn).

This path is reached from iso_sock_recvmsg() for a PA-sync broadcast

sink socket (BT_SK_DEFER_SETUP | BT_SK_PA_SYNC), so the dropped-lock

window can race with connection teardown driven by controller events.

Re-validate iso_pi(sk)->conn and its hcon after re-acquiring the socket

lock and bail out if the connection went away, as already done in the

sibling iso_sock_rebind_bc().