Heap-corruption when freeing allocated memory - c

Question

I am writing small school project, and I got stuck with error that I can't fix. When I try to free allocated memory, I get this error:
Here is the code that involves my char pointer temp:
1. Allocation of memory and setting starting value:
char *temprijec(int rng, RIJEC *B, int *len) {
int i;
char *temp=(char*)calloc(*len + 1, sizeof(char));
*len = strlen((B + rng)->rijec);
for (i = 0; i < *len; i++) {
if (i == 0) {
temp[i] = (B + rng)->rijec[i];
}
else if (i == (*len)) {
temp[i] = '\0';
}
else {
temp[i] = '_';
}
}
return temp;
}
2. Working with char pointer temp:
void tijek_igre(char*temp,RIJEC *B,int rng,int len,int*br2pok,int *pokpogreska,int *pokbr,char*pokch) {
int i;
printf("\nPogodi slovo ili rijec!");
*pokch = _getch();
for (i = 0; (B + rng)->rijec[i] != '\0'; i++) {
if (*pokch == (B + rng)->rijec[i]) {
temp[i] = *pokch;
}
}
for (i = 0; (B + rng)->rijec[i] != '\0'; i++) {
if (*pokch != (B + rng)->rijec[i]) {
(*br2pok)++;
if (*br2pok == len) {
(*pokpogreska)++;
}
}
}
for (i = 0; temp[i] != '\0'; i++) {
if (temp[i] != '_') {
(*pokbr)++;
}
}
}
Everything is fine until I try to free it with free(temp);

Answer 1

I fixed the error by changing the way I am passing variables to function,structure instead of pointers and now it works idk why but it works :).Tnx everyone for help.
Changed code:
VARIJABLE temprijec(VARIJABLE V, RIJEC *B) {
int i;
V.len = strlen((B + V.rng)->rijec);
V.temp = (char*)calloc(V.len + 1, sizeof(char));
for (i = 0; i < V.len + 1; i++) {
if (i == 0) {
V.temp[i] = (B + V.rng)->rijec[i];
}
else if (i == (V.len)) {
V.temp[i] = '\0';
}
else {
V.temp[i] = '_';
}
}
return V;
}
and
VARIJABLE tijek_igre(RIJEC *B, VARIJABLE V) {
int i;
printf("\nPogodi slovo ili rijec!");
V.ch = _getch();
for (i = 0; (B + V.rng)->rijec[i] != '\0'; i++) {
if (V.ch == (B + V.rng)->rijec[i]) {
V.temp[i] = V.ch;
}
}
for (i = 0; (B + V.rng)->rijec[i] != '\0'; i++) {
if (V.ch != (B + V.rng)->rijec[i]) {
(V.pogresno_slovo)++;
if (V.pogresno_slovo == V.len) {
(V.pogreska)++;
}
}
}
for (i = 0; V.temp[i] != '\0'; i++) {
if (V.temp[i] != '_') {
(V.tocno_slovo)++;
}
}
return V;
}