src/amqp_definitions.c, src/cbs.c exist memory double-free issues

[kydahe]

src/amqp_definitions.c and src/cbs.c exist memory double-free issues that free a memory which is already freed.

1. src/amqp_definitions.c
   In sasl_mechanisms_get_sasl_server_mechanisms function, the second parameter "sasl_server_mechanisms_value" memory could be freed by amqpvalue_destroy() in Line 10420, 10427, 10435 and then was freed again in the end of function (Line 10446).
   That means the "sasl_server_mechanisms_value" memory must be freed twice, leading to double free issues.

int sasl_mechanisms_get_sasl_server_mechanisms(SASL_MECHANISMS_HANDLE sasl_mechanisms, AMQP_VALUE* sasl_server_mechanisms_value)
{
    ...
                            else
                            {
                                AMQP_VALUE single_amqp_value = amqpvalue_create_symbol(sasl_server_mechanisms_single_value);
                                if (single_amqp_value == NULL)
                                {
                                    amqpvalue_destroy(*sasl_server_mechanisms_value);    //may be double-free issues
                                    result = MU_FAILURE;
                                }
                                else
                                {
                                    if (amqpvalue_add_array_item(*sasl_server_mechanisms_value, single_amqp_value) != 0)
                                    {
                                        amqpvalue_destroy(*sasl_server_mechanisms_value);    //may be double-free issues
                                        amqpvalue_destroy(single_amqp_value);
                                        result = MU_FAILURE;
                                    }
                                    else
                                    {
                                        if (amqpvalue_set_composite_item(sasl_mechanisms_instance->composite_value, 0, *sasl_server_mechanisms_value) != 0)
                                        {
                                            amqpvalue_destroy(*sasl_server_mechanisms_value);    //may be double-free issues
                                            result = MU_FAILURE;
                                        }
                                        else
                                        {
                                            result = 0;
                                        }
                                    }

                                    amqpvalue_destroy(single_amqp_value);
                                }
                                amqpvalue_destroy(*sasl_server_mechanisms_value);    //Double-Free issue.
                            }
                        }
                        else
                        {
                            result = 0;
                        }
                    }
                }
            }
        }
    }

    return result;
}

2. src/cbs.c
   https://github.com/Azure/azure-uamqp-c/blob/master/src/cbs.c
   In cbs_put_token_async function, "token_value" memory is freed by message_set_body_amqp_value() in Line 549 first. And then "token_value" memory is freed again in the end of function (Line 639) by amqpvalue_destroy(), causing double free issues.

ASYNC_OPERATION_HANDLE cbs_put_token_async(CBS_HANDLE cbs, const char* type, const char* audience, const char* token, ON_CBS_OPERATION_COMPLETE on_cbs_put_token_complete, void* on_cbs_put_token_complete_context)
{
    ...
                /* Codes_SRS_CBS_01_009: [ The body of the message MUST contain the token. ]*/
                if (message_set_body_amqp_value(message, token_value) != 0)    //!!! token_value is freed by message_set_body_amqp_value
                {
                    /* Codes_SRS_CBS_01_072: [ If constructing the message fails, `cbs_put_token_async` shall fail and return a non-zero value. ]*/
                    LogError("Failed setting the token in the message body");
                    result = NULL;
                }
    ...
            message_destroy(message);    //!!! token_value is freed again --- Double Free issues
        }
    }

    return result;
}