+// This define is used to limit the depth of recursive readPageTree calls
+// This is needed because the page tree nodes can reference their parents
+// leaving us in an infinite loop
+// Most sane pdf documents don't have a call depth higher than 10
+#define MAX_CALL_DEPTH 1000
+
//------------------------------------------------------------------------
// Catalog
//------------------------------------------------------------------------
@@ -76,7 +82,7 @@
pageRefs[i].num = -1;
pageRefs[i].gen = -1;
}
- numPages = readPageTree(pagesDict.getDict(), NULL, 0);
+ numPages = readPageTree(pagesDict.getDict(), NULL, 0, 0);
if (numPages != numPages0) {
error(-1, "Page count in top-level pages object is incorrect");
}
@@ -170,7 +176,7 @@
return s;
}
-int Catalog::readPageTree(Dict *pagesDict, PageAttrs *attrs, int start) {
+int Catalog::readPageTree(Dict *pagesDict, PageAttrs *attrs, int start, int callDepth) {
Object kids;
Object kid;
Object kidRef;
@@ -220,9 +226,13 @@
// This should really be isDict("Pages"), but I've seen at least one
// PDF file where the /Type entry is missing.
} else if (kid.isDict()) {
- if ((start = readPageTree(kid.getDict(), attrs1, start))
- < 0)
- goto err2;
+ if (callDepth > MAX_CALL_DEPTH) {
+ error(-1, "Limit of %d recursive calls reached while reading the page tree. If your document is correct and not a test to try to force a crash, please report a bug.", MAX_CALL_DEPTH);
+ } else {
+ if ((start = readPageTree(kid.getDict(), attrs1, start, callDepth + 1))
+ < 0)
+ goto err2;
+ }
} else {
error(-1, "Kid object (page %d) is wrong type (%s)",
start+1, kid.getTypeName());
--- kpdf/xpdf/Catalog.h
+++ kpdf/xpdf/Catalog.h
@@ -82,7 +82,7 @@
Object outline; // outline dictionary
GBool ok; // true if catalog is valid
- int readPageTree(Dict *pages, PageAttrs *attrs, int start);
+ int readPageTree(Dict *pages, PageAttrs *attrs, int start, int callDepth);
Object *findDestInTree(Object *tree, GString *name, Object *obj);
};
