Start. ---Thread-Announcement------------------------------------------ Thread #x was created ... by 0x........: pthread_create@* (hg_intercepts.c:...) by 0x........: main (free_is_write.c:32) ---Thread-Announcement------------------------------------------ Thread #x is the program's root thread ---------------------------------------------------------------- Possible data race during write of size 1 at 0x........ by thread #x Locks held: none at 0x........: free (vg_replace_malloc.c:...) by 0x........: thread_func (free_is_write.c:15) by 0x........: mythread_wrapper (hg_intercepts.c:...) ... This conflicts with a previous read of size 1 by thread #x Locks held: none at 0x........: main (free_is_write.c:36) Address 0x........ is 5 bytes inside an unallocated block of size 16 in arena "client" Done. ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)