kern/75758: Hard system hangs on tty code

[Slawa Olhovchenkov]

>Number:         75758
>Category:       kern
>Synopsis:       Hard system hangs on tty code
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jan 03 18:50:20 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Slawa Olhovchenkov
>Release:        FreeBSD 6.0-CURRENT i386
>Organization:
no
>Environment:
System: FreeBSD notebook.acropolis.ru 6.0-CURRENT FreeBSD 6.0-CURRENT #5: Mon Jan 3 13:33:38 MSK 2005 root at notebook.acropolis.ru:/usr/obj/usr/src/sys/BOOK i386

	i386, FreeBSD 6.0-CURRENT i386
>Description:

6-current totally hangs by this program, from user, not root.
No responds on keys pressed, Control-Alt-ESC, switching console and etc.

System run in infinite loop in sys/kern/tty.c:ttread()

===
read:
        splx(s);
        /*
         * Input present, check for input mapping and processing.
         */
        first = 1;
        if (ISSET(lflag, ICANON | ISIG))
                goto slowcase;
        for (;;) {
                char ibuf[IBUFSIZ];
                int icc;

                icc = imin(uio->uio_resid, IBUFSIZ);
/* XXX uio_resid==0 => icc=0 */
                icc = q_to_b(qp, ibuf, icc);
/* icc == 0 */
                if (icc <= 0) {
                        if (first)
                                goto loop;

===

>How-To-Repeat:

Run this test program and type any. System immediately hangs.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

#define cfmakeraw(ptr) (ptr)->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR\
                                         |IGNCR|ICRNL|IXON);\
                       (ptr)->c_oflag &= ~OPOST;\
                       (ptr)->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);\
                       (ptr)->c_cflag &= ~(CSIZE|PARENB);\
                       (ptr)->c_cflag |= CS8


int
main(int argc, char *argv[])
{
        int     fd,
                i;
        char *buf[1024];

        struct termios tcn;
        if ((fd = open("/dev/tty", O_RDWR | O_NONBLOCK)) == -1) {
                return -1;      /* errno already set */
        }

        /* Set the tty to raw and to the correct speed */
        tcgetattr(fd, &tcn);

        tcn.c_oflag     = 0;
        tcn.c_iflag     = IGNBRK | IGNPAR;
        tcn.c_cflag     = CREAD | CLOCAL | CS8;

        tcn.c_lflag = NOFLSH;

        cfmakeraw(&tcn);

        for (i = 0; i < 16; i++)
                tcn.c_cc[i] = 0;

        tcn.c_cc[VMIN]  = 1;
        tcn.c_cc[VTIME] = 0;

        tcsetattr(fd, TCSANOW, &tcn);

        if ((i = fcntl(fd, F_GETFL, 0)) != -1) {
                i &= ~O_NONBLOCK;
                fcntl(fd, F_SETFL, i);
        }
        read(fd, buf, 0);

}                                                                                                                                              

>Fix:

	


>Release-Note:
>Audit-Trail:
>Unformatted: