Package: valgrind
Version: 1:3.8.1-1
Severity: normal
Tags: patch
If i link the simple program below with -lpthread, then valgrind
reports a block of 32 bytes still-reachable from calloc within
dlopen().
If i do not link with -lpthread, then valgrind reports no errors.
0 dkg@alice:~$ cat dlopentest.c
#include <dlfcn.h>
#include <stdio.h>
int main() {
void* x;
int j;
x = dlopen("/usr/lib/x86_64-linux-gnu/libm.so", RTLD_LOCAL | RTLD_NOW);
j = dlclose(x);
printf("result: %d\n", j);
printf("bar: %s\n", dlerror());
return 0;
}
0 dkg@alice:~$ gcc -g -Wall -Werror --pedantic --std=c99 -o dlopentest -ldl
-lpthread dlopentest.c
0 dkg@alice:~$ valgrind --leak-check=full --show-reachable=yes -- ./dlopentest
==10368== Memcheck, a memory error detector
==10368== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==10368== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==10368== Command: ./dlopentest
==10368==
result: 0
bar: (null)
==10368==
==10368== HEAP SUMMARY:
==10368== in use at exit: 32 bytes in 1 blocks
==10368== total heap usage: 6 allocs, 5 frees, 1,494 bytes allocated
==10368==
==10368== 32 bytes in 1 blocks are still reachable in loss record 1 of 1
==10368== at 0x4C280A4: calloc (vg_replace_malloc.c:593)
==10368== by 0x4E3235F: _dlerror_run (dlerror.c:142)
==10368== by 0x4E31EE0: dlopen@@GLIBC_2.2.5 (dlopen.c:88)
==10368== by 0x400672: main (dlopentest.c:7)
==10368==
==10368== LEAK SUMMARY:
==10368== definitely lost: 0 bytes in 0 blocks
==10368== indirectly lost: 0 bytes in 0 blocks
==10368== possibly lost: 0 bytes in 0 blocks
==10368== still reachable: 32 bytes in 1 blocks
==10368== suppressed: 0 bytes in 0 blocks
==10368==
==10368== For counts of detected and suppressed errors, rerun with: -v
==10368== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 7 from 7)
0 dkg@alice:~$
I discovered this while investigating what looked like leaks in
p11-kit, and Stef Walter suggested that the right approach here is
probably just to ask for a valgrind suppression for this particular
leak.
http://lists.freedesktop.org/archives/p11-glue/2013-February/000263.html
I've tested by adding a suppression like the following, and it does
seem to suppress this particular warning:
--- a/usr/lib/valgrind/debian-libc6-dbg.supp 2012-09-19 13:59:48.000000000
-0400
+++ b/usr/lib/valgrind/debian-libc6-dbg.supp 2013-02-18 17:26:16.162482140
-0500
@@ -34,3 +34,11 @@
fun:__pthread_initialize_manager
fun:pthread_create@@GLIBC_2.1
}
+{
+ Debian libpthread (libc6-dbg) - dlopen
+ Memcheck:Leak
+ fun:calloc
+ fun:_dlerror_run
+ fun:dlopen@@GLIBC_2.2.5
+ fun:main
+}
If you decide that this is actually a problem with libc6 instead, feel
free to forward this bug report to that package, and i'll try to help
other people replicate the problem if that's useful.
Thanks for maintaining valgrind in debian!
--dkg
-- System Information:
Debian Release: 7.0
APT prefers testing
APT policy: (500, 'testing'), (200, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Kernel: Linux 3.7-trunk-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages valgrind depends on:
ii libc6 2.13-38
ii libc6-dbg 2.13-38
Versions of packages valgrind recommends:
ii gdb 7.4.1+dfsg-0.1
ii valgrind-dbg 1:3.8.1-1
Versions of packages valgrind suggests:
pn alleyoop <none>
pn kcachegrind <none>
pn valgrind-mpi <none>
pn valkyrie <none>
-- no debconf information
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