Invalid write of size 1
   at 0x........: bad_things (threadname.c:21)
   by 0x........: main (threadname.c:82)
 Address 0x........ is 0 bytes after a block of size 1 alloc'd
   at 0x........: malloc (vg_replace_malloc.c:...)
   by 0x........: bad_things (threadname.c:20)
   by 0x........: main (threadname.c:82)

Thread 2:
Invalid write of size 1
   at 0x........: bad_things (threadname.c:21)
   by 0x........: child_fn_0 (threadname.c:67)
   ...
 Address 0x........ is 0 bytes after a block of size 2 alloc'd
   at 0x........: malloc (vg_replace_malloc.c:...)
   by 0x........: bad_things (threadname.c:20)
   by 0x........: child_fn_0 (threadname.c:67)
   ...

Thread 3 try1:
Invalid write of size 1
   at 0x........: bad_things (threadname.c:21)
   by 0x........: child_fn_1 (threadname.c:51)
   ...
 Address 0x........ is 0 bytes after a block of size 3 alloc'd
   at 0x........: malloc (vg_replace_malloc.c:...)
   by 0x........: bad_things (threadname.c:20)
   by 0x........: child_fn_1 (threadname.c:51)
   ...

I am in child_fn_1
Thread 4 012345678901234:
Invalid write of size 1
   at 0x........: bad_things (threadname.c:21)
   by 0x........: child_fn_2 (threadname.c:35)
   ...
 Address 0x........ is 0 bytes after a block of size 4 alloc'd
   at 0x........: malloc (vg_replace_malloc.c:...)
   by 0x........: bad_things (threadname.c:20)
   by 0x........: child_fn_2 (threadname.c:35)
   ...

Thread 1:
Invalid write of size 1
   at 0x........: bad_things (threadname.c:21)
   by 0x........: main (threadname.c:90)
 Address 0x........ is 0 bytes after a block of size 5 alloc'd
   at 0x........: malloc (vg_replace_malloc.c:...)
   by 0x........: bad_things (threadname.c:20)
   by 0x........: main (threadname.c:90)