linux-kernel - x86_64 system lockup from userspace using setitimer()

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Message-ID: <45F6F3A6.9060405@gmx.de>
Date:	Tue, 13 Mar 2007 19:55:34 +0100
From:	Johannes Bauer <JohannesBauer@....de>
To:	linux-kernel@...r.kernel.org
Subject: x86_64 system lockup from userspace using setitimer()

Dear Community,

I think I've encountered a bug with the Linux kernel which results in a 
complete system lockup and which can be started without root priviliges. 
It's reproducible with 2.6.20.1 and 2.6.20.2 and only x64_64 seems affected.

Here's the code which triggers the bug (originally found by me using an 
only partly initialized "struct itimerval" structure - hence the strange 
values in it_interval):

-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----
#include <stdio.h>
#include <sys/time.h>
#include <unistd.h>

int main(int argc, char **argv) {
     struct itimerval tim = {
         .it_interval = {
             .tv_sec = 140735669863712,
             .tv_usec = 4199521
         },
         .it_value = {
             .tv_sec = 0,
             .tv_usec =  100000
         }
     };
     setitimer(ITIMER_REAL, &tim, NULL);
     while (1) sleep(1);
     return 0;
}
-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----

Compiled with gcc 4.1.1 with "gcc -O2 -Wall -o crash crash.c".

The sourcecode can be found at 
http://www.johannes-bauer.com/crash/crash.c and my kernel configuration 
is at http://www.johannes-bauer.com/crash/config

Any further questions: feel free to ask. Please CC me for any posts in 
this thread.

Greetings,
Johannes

-- 
"A PC without Windows is like a chocolate cake without mustard."

Johannes Bauer
91054 Erlangen
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