I get overly curious about esoteric technical crap, so I wrote a test case for > 4gb pointers within this scenario. Still no corruption occurs. This is ubuntu 14 w/ 64bit btw.

root@oil:/root/git/blockparty_repo/tmp# cat ./test.c 
#include <stdio.h>

int main()
{

    // simple int pointer
    int *tmp = NULL;

    // loop to alloc memory till we get > 4gb
    for(;;)
    {
        tmp = (int *) malloc(100000000);
        if(tmp > (unsigned int) -1)
            break;
    }

    // alloc arbitrary chunk (clear alloc)
    tmp = (int *) calloc(sizeof(int) * 10, 1);

    // diplay the pointer
    printf("\n tmp: %p - %u\n\n", tmp, tmp[0]);

    // return 4byte index
    return tmp[0];

}
root@oil:/root/git/blockparty_repo/tmp# gcc ./test.c 
./test.c: In function \u2018main\u2019:
./test.c:12:17: warning: incompatible implicit declaration of         built-in function \u2018malloc\u2019 [enabled by default]
   tmp = (int *) malloc(100000000);
                 ^
./test.c:13:10: warning: comparison between pointer and integer [enabled by default]
   if(tmp > (unsigned int) -1)
          ^
./test.c:18:16: warning: incompatible implicit declaration of built-in function \u2018calloc\u2019 [enabled by default]
  tmp = (int *) calloc(sizeof(int) * 10, 1);
                ^
root@oil:/root/git/blockparty_repo/tmp# valgrind ./a.out
==4704== Memcheck, a memory error detector
==4704== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==4704== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==4704== Command: ./a.out
==4704== 

 tmp: 0x34cf5040 - 0

==4704== 
==4704== HEAP SUMMARY:
==4704==     in use at exit: 4,300,000,040 bytes in 44 blocks
==4704==   total heap usage: 44 allocs, 0 frees, 4,300,000,040 bytes allocated
==4704== 
==4704== LEAK SUMMARY:
==4704==    definitely lost: 3,700,000,040 bytes in 38 blocks
==4704==    indirectly lost: 0 bytes in 0 blocks
==4704==      possibly lost: 600,000,000 bytes in 6 blocks
==4704==    still reachable: 0 bytes in 0 blocks
==4704==         suppressed: 0 bytes in 0 blocks
==4704== Rerun with --leak-check=full to see details of leaked memory
==4704== 
==4704== For counts of detected and suppressed errors, rerun with: -v
==4704== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
root@oil:/root/git/blockparty_repo/tmp#