corrupted double-linked

["GHui" <ugiwgh@xxxxxxxxx>]

I had coding a program like the following.
#include <stdio.h>
int main(int argc,char **argv)
{
    int *a=(int*)malloc(sizeof(int));
    free(a);
    free(a);
    return 0;
}
The program will get error "double free or corruption (fasttop)".
I have another question. I have got an error message "corrupted double-linked". What code can result in this? And its killed signal. 
Any help will be appreciated.

Thanks,
GHui