$ gdb /usr/local/bin/perl  core
...
Core was generated by `/usr/local/bin/perl -lw ./959669.pl 128'.
Program terminated with signal 11, Segmentation fault.
#0  0x00007f8382eb85c5 in new (classname=0x11b1170 "fred", bits=<optimized out>) at test.xs:23
23	    SvLEN_set( obj, bytes );
(gdb) q

##</code><code>##

...
    obj = newSV_type(SVt_PV);
    SvPOK_only( obj );
    SvPV_set( obj, vector );
    SvLEN_set( obj, bytes );
    SvCUR_set( obj, bytes );
...

__END__
$ ./959669.pl 128
...
SV = PVMG(0x1068f90) at 0xfb8d80
  REFCNT = 1
  FLAGS = (OBJECT,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x149cfa0 "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
  CUR = 16
  LEN = 16
  STASH = 0xfd4f08	"fred"