pdf: filter order tracking implementation (max:64)

libclamav/pdf.c

@@ -1429,6 +1429,10 @@ static void handle_pdfname(struct pdf_struct *pdf, struct pdf_obj *obj, const ch
         return;
     }
 
+    /* record filter order */
+    if ((*state == STATE_FILTER) && ((1 << act->set_objflag) & KNOWN_FILTERS))
+        obj->filterlist[obj->numfilters++] = act->set_objflag;
+
     if ((act->nameflags & NAMEFLAG_HEURISTIC) && escapes) {
         /* if a commonly used PDF name is escaped that is certainly
            suspicious. */

libclamav/pdf.h

@@ -22,11 +22,14 @@
 #define __PDF_H
 
 #include "others.h"
+#define PDF_FILTERLIST_MAX 64
 struct pdf_obj {
     uint32_t start;
     uint32_t id;
     uint32_t flags;
     uint32_t statsflags;
+    uint32_t numfilters;
+    uint32_t filterlist[PDF_FILTERLIST_MAX];
     char *path;
 };