Segmentation fault initialising an array

The following program produces a segmentation fault, and I'm not sure why. `malloc` succeeds, so it doesn't seem to be an initialisation error, but for some reason, it segfaults when I access the 253900th element. The array is only 4 * 1e6 bytes, or a about a Megabyte. This does produce a lot of output ``` #include <stdlib.h> #include <stdio.h> int *long_array(size_t N) { int *arr = (int *) malloc(N); if (arr == NULL) { printf("could not malloc"); exit(1); } for (size_t i = 0; i < N; i++) { printf(".. %ld ", i); arr[i] = 10; } printf("done with loop\n"); return arr; } int main(void) { int *arr = long_array(1000000); printf("%d", arr[5050]); return 0; } ``` I compile this with `gcc -std=c99` and run the output to see the final few numbers printed before the segfault: ``` 253899 .. 253900 .. 2 segmentation fault (core dumped) ./a.out ``` I don't understand why accessing a particular index is causing the segmentation fault. I can guess that I must be accessing a memory location outside of my processes address space, but this seems like a bug if I successfully allocated the memory from within my address space.