https://bugs.kde.org/show_bug.cgi?id=437790
Bug ID: 437790
Summary: valgrind reports "Conditional jump or move depends on
uninitialised value" in memchr of macOS 10.15
Product: valgrind
Version: unspecified
Platform: MacPorts Packages
OS: macOS
Status: REPORTED
Severity: minor
Priority: NOR
Component: memcheck
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
valgrind reports "Conditional jump or move depends on uninitialised value" in
memchr of macOS 10.15 with a very simple program test:
#include <stdio.h>
#include <string.h>
# cat test.c
int main(int argc, char *argv[])
{
char strval[100];
int len = sprintf(strval, "%.7G", 10.);
if(memchr(strval, '.', len))
printf("IF len %d\n", len);
else
printf("ELSE len %d\n", len);
}
STEPS TO REPRODUCE
1. In a macOS 10.15:
$ cc -o test test.c
2. valgrind test
OBSERVED RESULT
3. Results:
==51455== Conditional jump or move depends on uninitialised value(s)
==51455== at 0x100617108: _platform_memchr$VARIANT$Base (in
/usr/lib/system/libsystem_platform.dylib)
==51455== by 0x100003ECB: main (kk.c:11)
EXPECTED RESULT
According to POSIX
(https://pubs.opengroup.org/onlinepubs/9699919799/functions/memchr.html) memchr
should behave as it would read byte by byte until the character is found up to
the len parameter. Since len is also the number of characters written by
sprintf it shouldn't be the case that memchr reads uninitialised values
SOFTWARE/OS VERSIONS
macOS: 10.15
valgrind valgrind-3.17.0.GIT-lbmacos installed from macports.
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