re PR libfortran/81938 (valgrind error message and heap-buffer-overflow on…

re PR libfortran/81938 (valgrind error message and heap-buffer-overflow on address sanitized libgfortran.so)

2017-10-27  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
	    Rimvydas (RJ)

	PR libgfortran/81938
	io/format.c (free_format_data): Don't try to free vlist
	descriptors past the end of the fnode array.

From-SVN: r254163

libgfortran/ChangeLog

+2017-10-27  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
+	    Rimvydas (RJ)
+
+	PR libgfortran/81938
+	io/format.c (free_format_data): Don't try to free vlist
+	descriptors past the end of the fnode array.
+	
 2017-10-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR libfortran/82233

libgfortran/io/format.c

@@ -266,7 +266,8 @@ free_format_data (format_data *fmt)
     return;
 
   /* Free vlist descriptors in the fnode_array if one was allocated.  */
-  for (fnp = fmt->array.array; fnp->format != FMT_NONE; fnp++)
+  for (fnp = fmt->array.array; fnp < &fmt->array.array[FARRAY_SIZE] &&
+       fnp->format != FMT_NONE; fnp++)
     if (fnp->format == FMT_DT)
 	{
 	  if (GFC_DESCRIPTOR_DATA(fnp->u.udf.vlist))