I have run my application with valgrind in a script file with the command :
"/usr/local/bin/valgrind --tool -v ./my_application".
The OS is Linux RedHat 7.2

When the application executes the code line "system(cmd)", the application is 
frozen. 

I join all the lines printed by valgrind and my application :
==32001== Nulgrind, a binary JIT-compiler for x86-linux.
==32001== Copyright (C) 2002-2004, and GNU GPL'd, by Nicholas Nethercote.
==32001== Using valgrind-2.1.1, a program supervision framework for x86-linux.
==32001== Copyright (C) 2000-2004, and GNU GPL'd, by Julian Seward.
==32001== Valgrind library directory: /usr/local/lib/valgrind
==32001== Command line
==32001==    ./SCG
==32001== Startup, with flags:
==32001==    --tool=none
==32001==    -v
==32001== Reading syms from /cfg/conf_exe/SCG (0x8048000)
==32001== Reading syms from /lib/ld-2.2.4.so (0x81000000)
==32001== Reading syms from /lib/ld-2.2.4.so (0xB0000000)
==32001== Reading syms from /usr/local/lib/valgrind/vgskin_none.so (0xB0017000)
==32001== Reading syms from /lib/libdl-2.2.4.so (0xB002B000)
==32001== Reading syms from /lib/i686/libc-2.2.4.so (0xB002F000)
==32001== Reading syms from /usr/local/lib/valgrind/stage2 (0xB8000000)
--32001-- warning: line info addresses out of order at entry 939: 0xB800BD39 
0x700179D9
--32001-- warning: line info addresses out of order at entry 943: 0xB800BD4E 
0x700179EE
--32001-- warning: line info addresses out of order at entry 1012: 0xB800BE8A 
0x70017D02
--32001-- warning: line info addresses out of order at entry 1015: 0xB800BE8A 
0x70017D12
--32001-- warning: line info addresses out of order at entry 1313: 0xB800C614 
0x70018C14
--32001-- warning: line info addresses out of order at entry 1317: 0xB800C633 
0x70018C2B
--32001-- warning: line info addresses out of order at entry 13383: 0xB80236D6 
0x70046D71
--32001-- warning: line info addresses out of order at entry 13387: 0xB80236EC 
0x70046D80
--32001-- warning: line info addresses out of order at entry 27583: 0xB803A30E 
0x700745F4
--32001-- warning: line info addresses out of order at entry 27586: 0xB803A318 
0x700745F8
--32001-- warning: line info addresses out of order at entry 27588: 0xB803A318 
0x700745F8
--32001-- warning: line info addresses out of order at entry 27591: 0xB803A31A 
0x700745FA
--32001-- warning: line info addresses out of order at entry 27831: 0xB803A8C0 
0x70075110
--32001-- warning: line info addresses out of order at entry 27839: 0xB803A8FC 
0x7007514C
==32001== REDIRECT soname:libc.so.6(__GI___errno_location) to 
soname:libpthread.so.0(__errno_location)
==32001== REDIRECT soname:libc.so.6(__errno_location) to soname:libpthread.so.0
(__errno_location)
==32001== REDIRECT soname:libc.so.6(__GI___h_errno_location) to 
soname:libpthread.so.0(__h_errno_location)
==32001== REDIRECT soname:libc.so.6(__h_errno_location) to 
soname:libpthread.so.0(__h_errno_location)
==32001== REDIRECT soname:libc.so.6(__GI___res_state) to soname:libpthread.so.0
(__res_state)
==32001== REDIRECT soname:libc.so.6(__res_state) to soname:libpthread.so.0
(__res_state)
==32001== REDIRECT soname:libc.so.6(stpcpy) to *vgpreload_memcheck.so*(stpcpy)
==32001== REDIRECT soname:libc.so.6(strnlen) to *vgpreload_memcheck.so*(strnlen)
==32001== REDIRECT soname:ld-linux.so.2(stpcpy) to *vgpreload_memcheck.so*
(stpcpy)
==32001== REDIRECT soname:ld-linux.so.2(strchr) to *vgpreload_memcheck.so*
(strchr)
==32001==
==32001== Reading syms from /usr/local/lib/valgrind/vg_inject.so (0x8101A000)
==32001== Reading syms from /usr/X11R6/lib/libXm.so.2.1 (0x81031000)
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libXext.so.6.4 (0x811CE000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libXt.so.6.0 (0x811DD000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libX11.so.6.2 (0x8122A000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libXmu.so.6.2 (0x81309000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /lib/i686/libm-2.2.4.so (0x81322000)
==32001== Reading syms from /lib/i686/libc-2.2.4.so (0x81346000)
==32001== Reading syms from /usr/X11R6/lib/libSM.so.6.0 (0x81482000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libICE.so.6.3 (0x8148C000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /usr/X11R6/lib/libXp.so.6.2 (0x814A4000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
==32001== Reading syms from /lib/libnss_files-2.2.4.so (0x814AF000)
==32001== Reading syms from /usr/lib/gconv/ISO8859-15.so (0x81023000)
==32001==    object doesn't have a symbol table
==32001==    object doesn't have any debug info
Warning: Cannot convert string "user9x17" to type FontStruct

Systeme de Configuration Graphique - Version M1.13 - (c) AREVA T&D P&C
Etat courant : TRAVAIL
RETRIEVING DATA DESCRIPTION
system call : rm (rm schema.rgl)
system call : co (co -q -r1.11 SCH/schema.rgl,v)
proxy 32004 for tid 1 exited status -1, res 0
got signal 17 in LWP 32001 (32001)

valgrind: vg_signals.c:1557 (vg_async_signalhandler): Assertion 
`vgPlain_ksigismember(&uc->uc_sigmask, sigNo)' failed.
==32001==    at 0xB802BA64: vgPlain_skin_assert_fail (vg_mylibc.c:1211)

sched status:

Thread 1: status = Runnable, associated_mx = 0x0, associated_cv = 0x0
==32001==    at 0x813749C0: sigprocmask 
(../sysdeps/unix/sysv/linux/sigprocmask.c:48)
==32001==    by 0x81395710: system (../sysdeps/posix/system.c:145)
==32001==    by 0x80860A2: CONF_SYS (Bao.c:763)
==32001==    by 0x8098B6E: Tarch_get (Tarch.c:73)


Note: see also the FAQ.txt in the source distribution.
It contains workarounds to several common problems.

If that doesn't help, please report this bug to: valgrind.kde.org

In the bug report, send all the above text, the valgrind
version, and what Linux distro you are using.  Thanks.