Stanislav Meduna wrote:
> Am I seeing ghosts? Anyone got other mysterious
> problems with current UML kernel? Could it be that
> some state-saving method is corrupting fp registers
> or something like that? Was there some change in the
> UML / vanilla kernel recently?
Confirmed: I can reproduce openssl changing a double
value in unrelated process. I was not able to come
up with a code not relying on external software yet:
===
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <signal.h>
testdblchg()
{
volatile double x0 = 2.0;
volatile double x1;
int iter = 0;
fprintf(stderr, "Starting loop, pid=%d\n", getpid());
while(1)
{
++iter;
x1 = x0;
x0 += 1.0;
if (x0 != x1 + 1)
{
kill(getppid(), SIGTERM);
fprintf(stderr, "Double variable changed! pid=%d, iteration=%d,
should=%g,
is=%g\n", getpid(), iter, x1+1, x0);
exit(1);
}
sleep(1);
}
}
testcrypto()
{
while(1)
{
system("openssl genrsa -out /dev/null 4096");
sleep(1);
}
}
main()
{
if (fork() == 0)
testdblchg();
testcrypto();
}
===
Output:
$ ./a.out
Starting loop, pid=16920
Generating RSA private key, 4096 bit long modulus
......++
.......................................................................................................................................................................++
e is 65537 (0x10001)
Generating RSA private key, 4096 bit long modulus
...................................Double variable changed! pid=16920,
iteration=15,
should=nan, is=nan
Terminated
$ uname -a
Linux dirk 2.6.26 #1 Wed Jul 30 10:56:10 CEST 2008 i686 GNU/Linux
$ cat /proc/cpuinfo
processor : 0
vendor_id : User Mode Linux
model name : UML
mode : skas
host : Linux seldon-base 2.6.23.17 #2 SMP Sat Jun 21 15:04:22 CEST
2008 i686
bogomips : 4771.02
$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.1-2'
--with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix
--enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr
--enable-targets=all --enable-cld --enable-checking=release
--build=i486-linux-gnu
--host=i486-linux-gnu --target=i486-linux-gnu
Thread model: posix
gcc version 4.3.1 (Debian 4.3.1-2)
$ dpkg -l libc6
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name Version Description
+++-==============-==============-============================================
ii libc6 2.7-10 GNU C Library: Shared libraries
Regards
--
Stano
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