https://bugs.kde.org/show_bug.cgi?id=397313
Bug ID: 397313
Summary: False positive on long double "uninitialised bytes"
Product: valgrind
Version: 3.12 SVN
Platform: Other
URL: https://github.com/ornladios/ADIOS/issues/184#issuecom
ment-411739144
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: jsew...@acm.org
Reporter: axel.huebl@plasma.ninja
Target Milestone: ---
The following minimal example leads to a false positive in long double
variables on uninitialized bytes:
(minimal example by Norbert Podhorszki, ORNL)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
int main (int argc, char ** argv)
{
char filename[] = "test_longdouble_valgrind.data";
long double ld1 = 1.2345e+80;
long double *bufm = (long double *) malloc (sizeof(long double));
long double *bufc = (long double *) calloc (1, sizeof(long double));
memcpy (bufm, &ld1, sizeof(long double));
memcpy (bufc, &ld1, sizeof(long double));
int fd = creat(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
write(fd, bufm, sizeof(long double));
write(fd, bufc, sizeof(long double));
close(fd);
free(bufm);
free(bufc);
return 0;
}
Valgrind complains about both the malloc'd and calloc'd buffers.
$ valgrind ./test_longdouble_valgrind
==15574== Memcheck, a memory error detector
==15574== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==15574== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==15574== Command: ./test_longdouble_valgrind
==15574==
==15574== Syscall param write(buf) points to uninitialised byte(s)
==15574== at 0x4F312C0: __write_nocancel (syscall-template.S:84)
==15574== by 0x40083F: main (in
/home/adios/work/test/other_tests/test_longdouble_valgrind)
==15574== Address 0x520404a is 10 bytes inside a block of size 16 alloc'd
==15574== at 0x4C2DB8F: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==15574== by 0x4007D8: main (in
/home/adios/work/test/other_tests/test_longdouble_valgrind)
==15574==
==15574== Syscall param write(buf) points to uninitialised byte(s)
==15574== at 0x4F312C0: __write_nocancel (syscall-template.S:84)
==15574== by 0x400855: main (in
/home/adios/work/test/other_tests/test_longdouble_valgrind)
==15574== Address 0x520409a is 10 bytes inside a block of size 16 alloc'd
==15574== at 0x4C2FB55: calloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==15574== by 0x4007EB: main (in
/home/adios/work/test/other_tests/test_longdouble_valgrind)
We are aware of the limitations listed here
http://valgrind.org/docs/manual/manual-core.html#manual-core.limits
but this still seems to be a bug.
Further information:
https://github.com/ornladios/ADIOS/issues/184#issuecomment-411728907
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