Valgrind-3.6.0-r11090
gcc version 4.4.3 (Gentoo 4.4.3 p1.0) (amd64)

Tried to use exp-ptrcheck for the first time:

==5905== exp-ptrcheck, a heap, stack and global array overrun detector
==5905== NOTE: This is an Experimental-Class Valgrind Tool
==5905== Copyright (C) 2003-2009, and GNU GPL'd, by OpenWorks Ltd et al.
==5905== Using Valgrind-3.6.0.SVN and LibVEX; rerun with -h for copyright info
==5905== Command: _mc-bin/bin/mc
==5905== Parent PID: 16866
==5905== 
==5905== Warning: invalid file descriptor -1 in syscall close()
==5905== Warning: invalid file descriptor -1 in syscall close()
sysno == 124
exp-ptrcheck: the 'impossible' happened:
   unhandled syscall
==6102==    at 0x38013327: report_and_quit (m_libcassert.c:191)
==6102==    by 0x3801338E: panic (m_libcassert.c:275)
==6102==    by 0x380133CB: vgPlain_tool_panic (m_libcassert.c:290)
==6102==    by 0x380037B2: h_post_syscall (h_main.c:2584)
==6102==    by 0x38050283: vgPlain_post_syscall (syswrap-main.c:1728)
==6102==    by 0x38050EFC: vgPlain_client_syscall (syswrap-main.c:1626)
==6102==    by 0x3804D92D: handle_syscall (scheduler.c:885)
==6102==    by 0x3804E789: vgPlain_scheduler (scheduler.c:1081)
==6102==    by 0x38077EB4: run_a_thread_NORETURN (syswrap-linux.c:94)

sched status:
  running_tid=1

Thread 1: status = VgTs_Runnable
==6102==    at 0x5B1F327: getsid (in /lib64/libc-2.10.1.so)
==6102==    by 0x4545BD: init_subshell (subshell.c:233)
==6102==    by 0x450C74: main (main.c:2186)