From owner-freebsd-hackers  Tue Mar  2  7:27:39 1999
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From: Emmanuel DELOGET <pixel@DotCom.FR>
Message-Id: <199903021526.PAA21720@excalibur.oceanis.net>
Subject: bug in sysctl_sysctl_name
To: hackers@FreeBSD.ORG (FreeBSD Hackers Mail List)
Date: Tue, 2 Mar 1999 16:26:33 +0100 (MET)
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Hi, hackers [sorry to disturb you] !

Experiencing with sysctls on different FreeBSD 
(mostly 2.2.8 and 3.1), it appears that I found an 
interesting bug in the sysctl code.

This is the program that shows this bug :

The normal invocation for this test program is 

	prg num1 num2 .... numN. 

It displays the value of the { num1, ... , numN } 
OID. 

Ex :
	./sysctl_test 1 1
will print the string :
	FreeBSD

Using this proggy with args 0 1 1 1 will gives
	kern.ostype

But... (there's allways a 'but') 

a) ./sysctl_test 0 1 5 1 --> panic on 3.1-RELEASE (trap 12,
supervisor read, page not present)
b) ./sysctl_test 0 1 5 0 --> reboot (without even panicing) 
on my 2.2.8

The fact is that is't not very good to force a reboot
when a syscall just failed :) 

looking at the code in 2.2.8 for the called function 
sysctl_sysctl_name, I can't figure what's happening.

/**** file sysctl_test.c ****************** cut here */
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/sysctl.h>

void main(int ac,char **av)
{
  int		oidnum[128];
  int		nlen,result;
  char		buffer[32768];
  int		buflen = 16384; /* so I'm sure... */
  char		c;
  
  if (ac < 2) {
    printf("usage : %s %s\n",
	   av[0],
	   "oidnum1 oidnum2 ... oidnumN");
    exit(-1);
  }
  
  for (nlen=1;nlen<ac;nlen++) {
    oidnum[nlen-1] = atoi(av[nlen]);
  }
  
  result = sysctl(oidnum,nlen-1,buffer,&buflen,NULL,0);
  if (result < 0) {
    perror("sysctl");
    exit(-1);
  }

  if (buflen <= 4) {
    printf("%d\n",(int)(*buffer));
    return;
  }
  for (nlen=0;nlen<buflen;nlen++) {
    c = buffer[nlen];
    if (c) {
      if (c == (char)0x0a) printf("\n");
      else {
	if (c < 32) {
	  printf("[%#.2x]",c);
	} else { 		
	  printf("%c",c);
	}
      }
    }
  }
  printf("\n");
}

/************************************* end of file */

-- 
____________________________________________________________________
Emmanuel DELOGET [pixel] pixel@{dotcom.fr,epita.fr}  ----  DotCom SA
--------------------------------------------------------------------


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