#include <stdio.h>

int main(int argc, char * argv[])
{
	const char * src = "mcheck test";
	char * ptr = (char *)malloc(sizeof(char) * 32);
	memcpy(ptr, src, strlen(src));
	ptr[32] = '\0';  
	printf("*ptr=%s\n", ptr);                                                                                                              

	free(ptr);
	ptr = NULL;
	printf("process end\n");

	return 0;
}

~/test <root@debian> 11:46:33 $ ./a.out 
*ptr=mcheck test
process end
~/test <root@debian> 11:46:34 $ MALLOC_CHECK_=1 ./a.out 
*ptr=mcheck test
*** glibc detected *** ./a.out: free(): invalid pointer: 0x0828c008 ***
process end
~/test <root@debian> 11:46:43 $ MALLOC_CHECK_=2 ./a.out 
*ptr=mcheck test
Aborted

gcc main.c -lmcheck

~/test <root@debian> 11:50:03 $ ./a.out 
*ptr=mcheck test..........
memory clobbered past end of allocated block
Aborted

#include <stdio.h>

int main(int argc, char * argv[])
{
	mcheck(NULL);                                                                                                                          
	const char * src = "mcheck test";
	char * ptr = (char *)malloc(sizeof(char) * 32);
	memcpy(ptr, src, strlen(src));
	ptr[32] = '\0';  
	printf("*ptr=%s\n", ptr);

	free(ptr);
	ptr = NULL;
	printf("process end\n");

	return 0;
}

~/test <root@debian> 11:50:55 $ ./a.out 
*ptr=mcheck test..........
memory clobbered past end of allocated block
Aborted