sctp: init active key for the new asoc in dupcook_a and dupcook_b

When processing a duplicate cookie-echo chunk, for case 'A' and 'B',
after sctp_process_init for the new asoc, if auth is enabled for the
cookie-ack chunk, the active key should also be initialized.

Otherwise, the cookie-ack chunk made later can not be set with auth
shkey properly, and a crash can even be caused by this, as after
Commit 1b1e0bc99474 ("sctp: add refcnt support for sh_key"), sctp
needs to hold the shkey when making control chunks.

Fixes: 1b1e0bc99474 ("sctp: add refcnt support for sh_key")
Reported-by: Jianwen Ji <jiji@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_statefuns.c

@@ -1794,6 +1794,9 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(
 			       GFP_ATOMIC))
 		goto nomem;
 
+	if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
+		goto nomem;
+
 	/* Make sure no new addresses are being added during the
 	 * restart.  Though this is a pretty complicated attack
 	 * since you'd have to get inside the cookie.
@@ -1906,6 +1909,9 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(
 			       GFP_ATOMIC))
 		goto nomem;
 
+	if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
+		goto nomem;
+
 	/* Update the content of current association.  */
 	sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,