While return si_addr with offset from sigwaitinfo

I am working on the signal handler to deal with reap signals, randomly I am getting the signal with offset when I call sigwaitinfo function. All the signal attributes are right, except for info.si_addr. This offset in info.si_addr is causing a segmentation fault.

This offset seems to be the same - I have tried removing the offset and that works, but I need a correct solution to go forward.

static void *signalHandler(void *vptr_args __attribute__((unused)))
  {
      sigset_t signal_set;
      siginfo_t info;

      sigemptyset(&signal_set);
      sigaddset(&signal_set, SIG_REAP);
      sigaddset(&signal_set, SIG_ISOC_CANCEL);
      sigaddset(&signal_set, SIGTERM);
      sigaddset(&signal_set, SIGPIPE);

      while (true) {
          int rc = sigwaitinfo(&signal_set, &info);
          //...
          if (rc > 0) 
{
            if(info.si_signo == SIG_REAP) 
               {
                 // Reap URBs after some simple checks
                 if ((info.si_code != SI_ASYNCIO) &&
                     (info.si_code != SI_KERNEL)) {
                      printf("Bad si_code %d in SIG_REAP", info.si_code);                      
                      continue;
                 } 
                   else {
                      printf("OK si_code %d in SIG_REAP", info.si_code);
                 }
                   struct usbdevfs_urb *ioctl_urb = (struct usbdevfs_urb*)info.si_addres
                  if (!ioctl_urb) {
                     printf("SIG_REAP gave NULL ioctl_urb");
                      continue;
                  }
                  UrbInfo *urbInfo = ioctl_urb->usercontext;
                  if (!urbInfo) {
                     printf("SIG_REAP gave NULL urbInfo");
                      continue;
}

You are misusing si_addr. It is available for only a limited number of signals, and those do not include any real-time signals.

Per POSIX, si_addr is not applicable for signals other than SIGILL, SIGFPE, SIGSEGV, and SIGBUS. Linux also provides si_addr data for SIGTRAP:

SIGILL, SIGFPE, SIGSEGV, SIGBUS, and SIGTRAP fill in si_addr with the address of the fault.

No other signals provide a value for si_addr.

The source code linux/kernel/signal.c that fills in si_addr clearly shows that si_addr is not used for any signals other than those listed.

Note that per the Linux signal(7) man page:

Real-time signals are distinguished by the following:

Multiple instances of real-time signals can be queued. By contrast, if multiple instances of a standard signal are delivered while that signal is currently blocked, then only one instance is queued.

If the signal is sent using sigqueue(3), an accompanying value (either an integer or a pointer) can be sent with the signal. If the receiving process establishes a handler for this signal using the SA_SIGINFO flag to sigaction(2), then it can obtain this data via the si_value field of the siginfo_t structure passed as the second argument to the handler. Furthermore, the si_pid and si_uid fields of this structure can be used to obtain the PID and real user ID of the process sending the signal.

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