Date: Tue, 2 Mar 1999 16:26:33 +0100 (MET) From: Emmanuel DELOGET <pixel@DotCom.FR> To: hackers@FreeBSD.ORG (FreeBSD Hackers Mail List) Subject: bug in sysctl_sysctl_name Message-ID: <199903021526.PAA21720@excalibur.oceanis.net>
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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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