Hi all,
I am trying to solve some hard-to-find issue with valgrind (which I
use regularly and is a great tool, BTW :)). As memcheck does not find
anything, I gave exp-ptrcheck a try.
While the program is memcheck-clean, I get lots of violations and have
not yet managed to find any failure in my code (what obviously does
not mean there are none;)). It looks like some machine instructions
used by glibc trigger these violations. Many are inside the
string-library (like strcmp()) and show sizes of 8 or 16. To me, it
almost looks like the string library is using extended load operations
which then cause this problem.
To "fix" one of these situations, I changed a strchr() call. Code
snippet is as follows:
#if 1
pModDirNext = (uchar *)strchr((char *)pModDirCurr, ':');
#else
for(pModDirNext = pModDirCurr
; *pModDirNext != '\0' && *pModDirNext != ':'
; pModDirNext++)
; /*DO NOTHING - all done in for() header*/
#endif
If I use strchr(), this violation is displayed:
==5980== Invalid read of size 16
==5980== at 0x303E27D838: __GI_strchr (in /lib64/libc-2.11.1.so)
==5980== by 0x4219A7: Load (modules.c:639)
==5980== by 0x41FE7F: UseObj (obj.c:1156)
==5980== by 0x4136DF: confClassInit (conf.c:1293)
==5980== by 0x412B33: rsrtInit (rsyslog.c:185)
==5980== by 0x40CB85: realMain (syslogd.c:2912)
==5980== by 0x303E21EB1C: (below main) (in /lib64/libc-2.11.1.so)
==5980== Address 0x4c26440 is 16 bytes inside the accessing pointer's
==5980== legitimate range, a block of size 31 alloc'd
==5980== at 0x4A046DD: malloc (vg_replace_malloc.c:195)
==5980== by 0x303E27F021: strdup (in /lib64/libc-2.11.1.so)
==5980== by 0x4211DE: SetModDir (modules.c:745)
==5980== by 0x421279: moduleClassInit (modules.c:887)
==5980== by 0x41F6BF: objClassInit (obj.c:1337)
==5980== by 0x412907: rsrtInit (rsyslog.c:139)
==5980== by 0x40CB85: realMain (syslogd.c:2912)
==5980== by 0x303E21EB1C: (below main) (in /lib64/libc-2.11.1.so)
==5980==
If I use my replacement code, no violation is displayed.
I am using valgrind 3.5.0 on amd64. Any help on this issue would be
deeply appreciated.
Thanks,
Rainer
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