C - Write access violation - c

Question

I have an error at the last line, in nullString, a function setting all the string to '\0' with a simple for()
void function ( unsigned char inputArray[], size_t inputSize )
{
size_t cellSize;
if (inputSize <= 256)
cellSize = 1;
else
cellSize = ceil(inputSize / 2 / 256) + 1;
// Sub Box
unsigned char subBox[255];
for (size_t line = 0; line < 255; line++)
subBox[line] = 0;
generate_SubBox(subBox, key);
// Sub Box
// Sub Box reverse
unsigned char subBox_Inverse[255];
for (size_t line = 0; line < 255; line++)
subBox_Inverse[line] = 0;
generate_SubBox_Inverse(subBox_Inverse, subBox, key);
// Sub Box reverse
unsigned char* inputArray2 = NULL;
inputArray2 = malloc(sizeof(unsigned char)* inputSize / 2);
verifyMalloc(inputArray2);
nullString(inputArray2, inputSize / 2);
unsigned char string_temp[3] = { 0 };
size_t w = 0;
for (size_t i = 0; i < inputSize / 2; i++)
{
string_temp[0] = inputArray[w];
string_temp[1] = inputArray[w + 1];
inputArray2[i] = strtoll(string_temp, NULL, 16);
w += 2;
}
}
I tried neutralizing line per line all instructions coming before nullString() by commenting them but it doesn't change anything.
If I neutralize nullString, the error comes after, at
inputArray2[i] = strtoll(...)
Hope you've got the answer :)
Thanks in advance !
EDIT:
Here is nullString:
void nullString(unsigned char input[], size_t length)
{
for (size_t x = 0; x < length; x++)
input[x] = '\0';
}
I commented all the instructions before nullString, the error is still there.
I also verified variables and they all look like good
EDIT 2:
verifyMalloc:
void verifyMalloc(int* pointer)
{
if (pointer == NULL)
{
perror("Erreur");
Sleep(15000);
exit(0);
}
}

Answer 1

Everything we're seeing is seriously hinting at you forgetting to #include <stdlib.h> (and ignoring the warnings resulting from that).
This is what might happens when you use malloc() without including stdlib.h in the same file:
the compiler consider the malloc() function to be declared implicitly, which means it is assuming that it's return types is int (instead of *void).
This might work when sizeof (int) is the same as sizeof (*void). But when int is 32-bits while pointers are 64-bits then the address returned by malloc() might lose half of it's bits and point to an invalid address.

Answer 2

Try using
void bzero(void *s, size_t n); or
void *memset(void *s, int c, size_t n);
instead of your nullString() and for()something[x]=0 loops.
Then, this does not make all of the array zeroed:
unsigned char string_temp[3] = { 0 };
This makes
string[0] = 0;
string[1] = god_knows;
string[2] = god_knows_not;
so either - unsigned char string_temp[3] = {0,0,0};
or bzero(string_temp,3);
Consequently, when you do this:
string_temp[0] = inputArray[w];
string_temp[1] = inputArray[w + 1];
inputArray2[i] = strtoll(string_temp, NULL, 16);
strtoll() will be guessing when to stop. No guarantee this would be at string_temp[2].
Then, this should be enough:
unsigned char* inputArray2 = malloc(sizeof(unsigned char) * inputSize / 2);
inputArray2 will be NULL if malloc failed, or a valid pointer if it succeeded.
You may want to check your inputSize / this_and_that arithmetics. Does it really deliver what you expect? You might be surprised by division result of integer operands.
This also looks suspicious:
inputArray2[i] = strtoll(string_temp, NULL, 16);
strtoll returns longlong integer but your inputArray2 is of unsigned char type. So you are trying to store 8 bytes (sizeof longlong = 8) and you reserved place only for one (sizeof char = 1)
Redeclare your inputArray2 as long long
long long *inputArray2 = malloc(sizeof(long long) * inputSize /2 );
And try this with memset():
size_t size = sizeof(long long) * inputSize/2;
//Do you really need long long? You are storing max three digits. uint_8 will be enough
long long* inputArray2 = malloc(size);
memset(inputArray2, 0, size);