ITS#9124 Check we have data to process in Cancel Exop

servers/slapd/cancel.c

@@ -34,7 +34,8 @@ int cancel_extop( Operation *op, SlapReply *rs )
 	Operation *o;
 	int rc;
 	int opid;
-	BerElement *ber;
+	BerElementBuffer berbuf;
+	BerElement *ber = (BerElement *)&berbuf;
 
 	assert( ber_bvcmp( &slap_EXOP_CANCEL, &op->ore_reqoid ) == 0 );
 
@@ -43,12 +44,14 @@ int cancel_extop( Operation *op, SlapReply *rs )
 		return LDAP_PROTOCOL_ERROR;
 	}
 
-	ber = ber_init( op->ore_reqdata );
-	if ( ber == NULL ) {
-		rs->sr_text = "internal error";
-		return LDAP_OTHER;
+	if ( op->ore_reqdata->bv_len == 0 ) {
+		rs->sr_text = "empty request data field";
+		return LDAP_PROTOCOL_ERROR;
 	}
 
+	/* ber_init2 uses reqdata directly, doesn't allocate new buffers */
+	ber_init2( ber, op->ore_reqdata, 0 );
+
 	if ( ber_scanf( ber, "{i}", &opid ) == LBER_ERROR ) {
 		rs->sr_text = "message ID parse failed";
 		return LDAP_PROTOCOL_ERROR;