CVE-2026-74536

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

Bluetooth: ISO: fix leaking sk after socket release

iso_sock_kill() tests !sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket ||

sock_flag(sk, SOCK_DEAD) for early return, but this is always true since

sock_orphan(sk) sets SOCK_DEAD, so the sk reference released by socket

always leaks, iso_sock_destruct is never called.

The socket reference also leaks when __iso_sock_close() does not set

SOCK_ZAPPED, since iso_conn_del() does not call iso_sock_kill() after

zapping.

Fix by replacing SOCK_DEAD by BT_SK_KILLED flag that is not used for

something else, and lock_sock to ensure iso_sock_kill() puts sk only

after socket release only once. Release and iso_conn_del may run

concurrently. Call iso_sock_kill() from iso_conn_del() to clean sk up

after zapping.

Remove call to iso_sock_kill() from iso_sock_close(), as it's generally

no-op there.