Auto release of stack variables in C

You could use the cleanup variable attribute in GCC. Please take a look at this:
http://echorand.me/site/notes/articles/c_cleanup/cleanup_attribute_c.html

Sample code:

#include <stdio.h>
#include <stdlib.h>

void free_memory(void **ptr)
{
    printf("Free memory: %p\n", *ptr);
    free(*ptr);
}

int main(void)
{
    // Define variable and allocate 1 byte, the memory will be free at
    // the end of the scope by the free_memory function. The free_memory 
    // function will get the pointer to the variable *ptr (double pointer
    // **ptr).
    void *ptr  __attribute__ ((__cleanup__(free_memory))) = malloc(1);
    return 0;
}

If you save the source code in a file named main.c, you could compile it with this command:

gcc main.c -o main

and verify if there are any memory leaks by:

valgrind ./main

Example output from valgrind:

==1026== Memcheck, a memory error detector
==1026== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==1026== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==1026== Command: ./main
==1026== 
Free memory: 0x51ff040
==1026== 
==1026== HEAP SUMMARY:
==1026==     in use at exit: 0 bytes in 0 blocks
==1026==   total heap usage: 1 allocs, 1 frees, 1 bytes allocated
==1026== 
==1026== All heap blocks were freed -- no leaks are possible
==1026== 
==1026== For counts of detected and suppressed errors, rerun with: -v
==1026== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)