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Prevent circular references in Type3 fonts

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In corrupt PDF documents Type3 fonts may introduce circular dependencies, thus resulting in the affected font(s) never loading and parsing/rendering never completing.
Note that I've not seen any real-world examples of this kind of font corruption, but the attached PDF document was rather found in https://github.com/pdf-association/safedocs/tree/main/Miscellaneous%20Targeted%20Test%20PDFs

*Please note:* That repository contains a number of reduced test-cases that are specifically intended to test interoperability (between PDF viewer) and parsing/rendering for various kinds of strange/corrupt PDF documents.
Some of the test-cases found there may thus not make sense to try and "fix" upfront, in my opinion, unless the problems are also found in real-world PDF documents.
This commit is contained in:
Jonas Jenwald 2022-01-13 17:36:36 +01:00
parent ea57ef116e
commit 53d4ee7990
4 changed files with 139 additions and 0 deletions
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10
src/core/evaluator.js
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@ -1155,6 +1155,10 @@ class PartialEvaluator {
}
}
if (this.parsingType3Font && this.type3FontRefs.has(fontRef)) {
return errorFont();
}
if (this.fontCache.has(fontRef)) {
return this.fontCache.get(fontRef);
}
@ -4183,6 +4187,12 @@ class TranslatedFont {
// make sense to only be able to render a Type3 glyph partially.
const type3Evaluator = evaluator.clone({ ignoreErrors: false });
type3Evaluator.parsingType3Font = true;
// Prevent circular references in Type3 fonts.
const type3FontRefs = new RefSet(evaluator.type3FontRefs);
if (this.dict.objId && !type3FontRefs.has(this.dict.objId)) {
type3FontRefs.put(this.dict.objId);
}
type3Evaluator.type3FontRefs = type3FontRefs;
const translatedFont = this.font,
type3Dependencies = this.type3Dependencies;