Index: tools/convbdf.c
===================================================================
--- tools/convbdf.c	(Revision 20098)
+++ tools/convbdf.c	(Arbeitskopie)
@@ -522,6 +522,17 @@
 
             if (encoding < 0)
                 continue;
+            
+            if (bby < -pf->descent) {
+                fprintf(stderr, "Error: character %d goes %d pixel(s) beyond the font's descent\n",
+                        encoding, -bby-pf->descent);
+                return 0;
+            }
+            if (bby + bbh > pf->ascent) {
+                fprintf(stderr, "Error: character %d goes %d pixel(s) beyond the font's ascent\n",
+                        encoding, bby + bbh - pf->ascent);
+                return 0;
+            }
 
             /* set bits offset in encode map*/
             if (pf->offset[encoding-pf->firstchar] != (unsigned int)-1) {