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From 3d35d209c19c1d3b09b794a0c863ba5de44a9c0a Mon Sep 17 00:00:00 2001
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From: Marek Kasik <mkasik@redhat.com>
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Date: Mon, 29 Oct 2018 17:44:47 +0100
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Subject: [PATCH] Avoid cycles in PDF parsing
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Mark objects being processed in Parser::makeStream() as being processed
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and check the mark when entering this method to avoid processing
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of the same object recursively.
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---
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poppler/Parser.cc | 15 +++++++++++++++
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poppler/XRef.h | 1 +
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2 files changed, 16 insertions(+)
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diff --git a/poppler/Parser.cc b/poppler/Parser.cc
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index bd4845ab..8f48efbe 100644
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--- a/poppler/Parser.cc
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+++ b/poppler/Parser.cc
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@@ -197,6 +197,18 @@ Stream *Parser::makeStream(Object &&dict, Guchar *fileKey,
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Stream *str;
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Goffset length;
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Goffset pos, endPos;
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+ XRefEntry *entry = nullptr;
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+
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+ if (xref && (entry = xref->getEntry(objNum, false))) {
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+ if (!entry->getFlag(XRefEntry::Parsing) ||
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+ (objNum == 0 && objGen == 0)) {
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+ entry->setFlag(XRefEntry::Parsing, true);
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+ } else {
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+ error(errSyntaxError, getPos(),
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+ "Object '{0:d} {1:d} obj' is being already parsed", objNum, objGen);
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+ return nullptr;
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+ }
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+ }
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// get stream start position
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lexer->skipToNextLine();
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@@ -278,6 +290,9 @@ Stream *Parser::makeStream(Object &&dict, Guchar *fileKey,
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// get filters
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str = str->addFilters(str->getDict(), recursion);
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+ if (entry)
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+ entry->setFlag(XRefEntry::Parsing, false);
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+
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return str;
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}
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diff --git a/poppler/XRef.h b/poppler/XRef.h
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index 11ee5e03..2eb2f9fd 100644
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--- a/poppler/XRef.h
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+++ b/poppler/XRef.h
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@@ -65,6 +65,7 @@ struct XRefEntry {
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enum Flag {
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// Regular flags
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Updated, // Entry was modified
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+ Parsing, // Entry is currently being parsed
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// Special flags -- available only after xref->scanSpecialFlags() is run
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Unencrypted, // Entry is stored in unencrypted form (meaningless in unencrypted documents)
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--
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2.19.1
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