kern/39814: A stopping process will be waked up by any signals.

[oshima-ya%yagoto-urayama.jp@localhost]

>Number:         39814
>Category:       kern
>Synopsis:       A stopping process will be waked up by any signals.
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Oct 27 15:15:00 +0000 2008
>Originator:     Yasushi Oshima
>Release:        NetBSD-current
>Organization:
>Environment:
NetBSD sweety 4.99.73 NetBSD 4.99.73 (GENERIC) #237: Tue Oct 21 07:52:35 JST 
2008  oshima@sweety:/usr/src/sys/arch/amd64/compile/GENERIC amd64


>Description:
I think a stopping process by SIGSTOP will be waked up by only SIGCONT signal.
However it seems that any signals wake up the process in current.

This is different from NetBSD 4.0 and other OSs.

>How-To-Repeat:
In the following program in NetBSD-current, the signal handler of the 
child-process that outputs the message 'Caught signal 30' to /tmp/xxx and exits 
will be called, and the parent-process will output the message 'kill: No such 
process'.

In NetBSD-4.0, the parent-process outputs 'PID  xxx still exists' and the 
child-process
 exists under stopping state. This child-process will catch the SIGUSR1 signal 
by 'kill -CONT PID'.


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

FILE *fp;

void handler(int sig)
{
        fprintf(fp,"Caught signal %d\n",sig);
        fclose(fp);
        exit(0);
}

main()
{
        pid_t pid;

        pid = fork();

        if ( pid == -1 ) {
                err(1,"fork"); 
        } else if ( pid != 0 ) {

                /* Main Process */

                printf ("PID:%d\n",pid);
                sleep(1);
                kill(pid, SIGSTOP);    /* send SIGSTOP to child */
                sleep(1);
                kill(pid, SIGUSR1);    /* send SIGUSR1 to child --- this signal 
will be pending */
                sleep(1);
                if (kill(pid,0)==0) {
                        printf("PID %d still exists.\n", pid);
                } else {
                        err(1,"kill");
                }
                exit(0);
        } else {
                /* Child Process */
                struct sigaction sa;
                memset(&sa,0,sizeof(sa));
                sa.sa_handler = handler;

                fp = fopen("/tmp/xxx","w");
                if (fp == NULL ) {
                        perror("fopen");
                        exit(1);
                }
                exit(0);
        } else {
                /* Child Process */

                struct sigaction sa;
                memset(&sa,0,sizeof(sa));

                fp = fopen("/tmp/xxx","w");
                if (fp == NULL ) {
                        perror("fopen");
                        exit(1);
                }
                close(0);
                close(1);
                close(2);

                setsid();
                sa.sa_handler = handler;
                sigaction(SIGUSR1, &sa, 0);

                while(1);    /* loop */
        }
}

>Fix:
unknown