In below code from apache server ajp_msg.c, any idea where the msg->max_size is coming from ?

I am trying to fix error message below :

ajp_msg_append_cvt_string(): BufferOverflowException 4 8186

**
*  Add a String in AJP message, and transform the String in ASCII
*  if convert is set and we're on an EBCDIC machine
*
* @param msg       AJP Message to get value from
* @param value     Pointer to String
* @param convert   When set told to convert String to ASCII
* @return          APR_SUCCESS or error
*/
apr_status_t ajp_msg_append_string_ex(ajp_msg_t *msg, const char *value,
                                      int convert)
{
    apr_size_t len;

    if (value == NULL) {
        return(ajp_msg_append_uint16(msg, 0xFFFF));
    }

    len = strlen(value);
    if ((msg->len   len   3) > msg->max_size) {
        return ajp_log_overflow(msg, "ajp_msg_append_cvt_string");
    }

    /* ignore error - we checked once */
    ajp_msg_append_uint16(msg, (apr_uint16_t)len);

    /* We checked for space !!  */
    memcpy(msg->buf   msg->len, value, len   1); /* including \0 */

    if (convert) {
        /* convert from EBCDIC if needed */
        ap_xlate_proto_to_ascii((char *)msg->buf   msg->len, len   1);
    }

    msg->len  = len   1;

    return APR_SUCCESS;
}

CodePudding user response：

Look at the max_packet_size attribute. The default value in AJP is 8192.

This attribute sets the maximal AJP packet size in Bytes. The maximum value you can set is 65536. If you change it from the default, you must also change the packetSize attribute of your AJP connector on the Tomcat side! The attribute packetSize is available in Tomcat 6.0.2 onwards. The above settings needs to be done in the tomcat-connector and tomcat itself (a corresponding setting must be made in the AJP element in Tomcat's conf/server.xml file).

See here for more details.

CodePudding user response：

It needed ProxyIOBufferSize in apache config and packetSize in tomcat config on AJP connection. The apache config number must be less than or equal to tomcat packetSize. safest is to make them equal.

both of them were set to 64 kb i.e. 65,536 max allowed.