[Bug libgcc/109712] Segmentation fault in linear_search_fdes

[carlosgalvezp at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109712

--- Comment #25 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Perhaps this is a stupid comment, but isn't "ob.s.b.encoding" uninitialized?

  /* inside find_fde_tail */
  struct object ob;

  ...

  ob.pc_begin = NULL;
  ob.tbase = NULL;
  ob.dbase = (void *) dbase;
  ob.u.single = (fde *) eh_frame;
  ob.s.i = 0;
  ob.s.b.mixed_encoding = 1;  /* Need to assume worst case.  */
  const fde *entry = linear_search_fdes (&ob, (fde *) eh_frame, (void *) pc);

Above, only "ob.s.b.mixed_encoding" is set, not "ob.s.b.encoding".

After that, "linear_search_fdes" expects that it's set:

static const fde *
linear_search_fdes (struct object *ob, const fde *this_fde, void *pc)
{
  const struct dwarf_cie *last_cie = 0;
  int encoding = ob->s.b.encoding;
  _Unwind_Ptr base = base_from_object (ob->s.b.encoding, ob);