CVE-2022-50243

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

sctp: handle the error returned from sctp_auth_asoc_init_active_key

When it returns an error from sctp_auth_asoc_init_active_key(), the active_key is actually not updated. The old sh_key will be freeed while it's still used as active key in asoc. Then an use-after-free will be triggered when sending patckets, as found by syzbot:

sctp_auth_shkey_hold+0x22/0xa0 net/sctp/auth.c:112 sctp_set_owner_w net/sctp/socket.c:132 [inline] sctp_sendmsg_to_asoc+0xbd5/0x1a20 net/sctp/socket.c:1863 sctp_sendmsg+0x1053/0x1d50 net/sctp/socket.c:2025 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:734

This patch is to fix it by not replacing the sh_key when it returns errors from sctp_auth_asoc_init_active_key() in sctp_auth_set_key(). For sctp_auth_set_active_key(), old active_key_id will be set back to asoc->active_key_id when the same thing happens.

This vulnerability is rated as Moderate impact for Red Hat Enterprise Linux because exploitation requires local access to establish SCTP associations and execute socket operations that manipulate authentication keys. The SCTP kernel module is not loaded by default on typical systems, and SCTP authentication requires specific configuration. Because unauthenticated remote network traffic cannot directly trigger the condition, the blast radius is confined to local denial of service or memory corruption.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.