Dynamic Struct Array Being Allocated to infinite size - c

Question

my task is to write a struct which reads data from file and realloc more memory if needed.
So Far I have done this:
The Struct:
typedef struct myprog
{
int id;
char name[100];
int price;
}myprog;
Read Function:
myprog* readFromFile(FILE* fP, char fileName[], myprog* reg, int* size)
{
fP = fopen(fileName, "r"); //Open Input File as read
if (fP == NULL) //If File is not found, do nothing
{
printf("File does not exist.");
}
else //Else read file line by line
{
printf("\nReading from File");
int x = 0;
char line[100];
char* split;
char* args[4];
while (fgets(line, 100, fP)) //Read the first line
{
if (x == MAX) //If Max Size is reached, increase it twice
{
int new_size = MAX * 2;
reg = (struct vara*)realloc(reg, new_size * sizeof(struct vara)); //Even if i comment these lines the code works :O
}
split = strtok(line, " "); //Split the line on space delimiter i.e {"1", "apple", "10"}
args[0] = split;
int i = 1;
while (split != NULL)
{
split = strtok(NULL, " ");
args[i] = split;
i++;
}
if (i != 3) //Checking if the args size is three
{
//Copy from args to struct
reg[x].id = atoi(args[0]); //Copy Number
strcpy(reg[x].name, args[1]); //Copy Name
reg[x].price = atoi(args[2]); //Copy Balance
x++;
}
}
(*size) = x;
printf("\nReading Completed!");
fclose(fP);
}
return reg;
}
Main Function:
void main()
{
char fileName[100];
FILE* fP = NULL;
printf("Enter file Name : ");
scanf("%s", fileName);
myprog* reg = malloc(MAX * sizeof * reg); //#define MAX 1
int size = 0;
reg = readFromFile(fP, fileName, reg, &size);
//Some Code below
}
The Problem I am facing:
When I run the code with MAX defined with 1, it reads any number of products from file without any memory leak errors. It even works without the realloc, can you please help me identify my mistake?
The data in input file is like this:
1 prod_a 15
2 prod_b 20