Package: libc6
Version: 2.18-4
Severity: normal
Dear Maintainer,
While debugging a problem building the debian-installer,
we came across a case where strcmp reports 2 strings equality whereas they are
not.
It's the comparaison between 2 translated entries '.' and '..'
that are translated to the string \0000 and \0001 in the genisoimage program.
This program was complaining that '.' and '..' both translated to '' and thus
cannot generate iso.
This was obviously wrong, so I narrowed the check to this case:
----------
cat test_strcmp.c<<EOF
#include <stdio.h>
#include <stdlib.h>
void main(void) {
char stra[2];
char strb[2];
int result = 0;
stra[0] = 0;
stra[1] = 0;
strb[0] = 1;
strb[1] = 0;
result = strcmp(stra,strb);
printf("result from strcmp('\\0000','\\0001' is %d)\n",result);
exit(0);
}
EOF
Building this program on sparc, 32bit or 64bit, optimized or not, the result is
0.
Patrick Bagget did some more investigation and found that any string composed
of a list of 1 followed by a 0 is miscompared.
Here's an example :
{ 0, 0 } //i.e. original test case. Fails, returns 0
{ 1, 0 }
{ 1, 0, 0 } //fails, returns 0.
{ 1, 1, 0 }
{ 1, 1, 0, 0 } //fails, returns 0.
{ 1, 1, 1, 0 }
{ 1, 1, 1, 0, 0 } //fails, returns 0.
{ 1, 1, 1, 1, 0 }
{ 1, 1, 1, 1, 0, 0 } //fails, returns 0.
{ 1, 1, 1, 1, 1, 0 }A
There's something wrong in the glibc implementation of strcmp for the case of
sparc, and sparc64.
-- System Information:
Debian Release: jessie/sid
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: sparc (sparc64)
Kernel: Linux 3.13-1-sparc64-smp (SMP w/1 CPU core)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages libc6 depends on:
ii libgcc1 1:4.8.2-16
libc6 recommends no packages.
Versions of packages libc6 suggests:
ii debconf [debconf-2.0] 1.5.52
pn glibc-doc <none>
ii locales 2.18-4
-- debconf information:
glibc/restart-failed:
* libraries/restart-without-asking: true
glibc/disable-screensaver:
glibc/upgrade: true
glibc/restart-services:
#include <stdio.h>
#include <stdlib.h>
void main(void) {
unsigned char stra[2];
unsigned char strb[2];
int result = 0;
stra[0] = 0;
stra[1] = 0;
strb[0] = 1;
strb[1] = 0;
result = strcmp(stra,strb);
printf("result from strcmp('\\0000','\\0001' is %d)\n",result);
result = memcmp(stra,strb,2);
printf("result from memcmp('\\0000','\\0001' is %d)\n",result);
exit(0);
}
