* Makefile.in (VERSION): Bump to 4.5.7.

* cplus-dem.c (demangle_args):  Validate index for previously
	seen type to guard against bogus values from malformed manglings.
	* valops.c (value_struct_elt_for_reference):  Guard against
	blindly using NULL return value from lookup_symbol.

gdb/cplus-dem.c

@@ -1578,7 +1578,9 @@ demangle_args (declp, type, work)
 #ifdef ARM_DEMANGLING
 	  t--;
 #endif
-	  if (t >= work -> ntypes)
+	  /* Validate the type index.  Protect against illegal indices from
+	     malformed type strings. */
+	  if ((t < 0) || (t >= work -> ntypes))
 	    {
 	      return (0);
 	    }