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Code Issues Releases Wiki Activity

Fix infinite loop in QPDFWriter (fixes #143)

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This commit is contained in:
Jay Berkenbilt 2017-08-12 07:35:04 -04:00
parent 36b3fe5af7
commit 8249a26d69
5 changed files with 30 additions and 0 deletions
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9
libqpdf/QPDFWriter.cc
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@ -1054,6 +1054,9 @@ QPDFWriter::enqueueObject(QPDFObjectHandle object)
// here. Instead, enqueue the object stream. Object // here. Instead, enqueue the object stream. Object
// streams always have generation 0. // streams always have generation 0.
int stream_id = this->object_to_object_stream[og]; int stream_id = this->object_to_object_stream[og];
// Detect loops by storing invalid object ID 0, which
// will get overwritten later.
obj_renumber[og] = 0;
enqueueObject(this->pdf.getObjectByID(stream_id, 0)); enqueueObject(this->pdf.getObjectByID(stream_id, 0));
} }
else else
@ -1079,6 +1082,12 @@ QPDFWriter::enqueueObject(QPDFObjectHandle object)
} }
} }
} }
else if (obj_renumber[og] == 0)
{
// This can happen if a specially constructed file
// indicates that an object stream is inside itself.
QTC::TC("qpdf", "QPDFWriter ignore self-referential object stream");
}
} }
else if (object.isArray()) else if (object.isArray())
{ {

1
qpdf/qpdf.testcov
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@ -294,3 +294,4 @@ QPDF ignore first extra space in xref entry 0
QPDF ignore second extra space in xref entry 0 QPDF ignore second extra space in xref entry 0
QPDF ignore length error xref entry 0 QPDF ignore length error xref entry 0
QPDF_encryption pad short parameter 0 QPDF_encryption pad short parameter 0
QPDFWriter ignore self-referential object stream 0

1
qpdf/qtest/qpdf.test
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@ -220,6 +220,7 @@ my @bug_tests = (
["106", "zlib data error", 3], ["106", "zlib data error", 3],
["141a", "/W entry size 0", 2], ["141a", "/W entry size 0", 2],
["141b", "/W entry size 0", 2], ["141b", "/W entry size 0", 2],
["143", "self-referential ostream", 3],
); );
$n_tests += scalar(@bug_tests); $n_tests += scalar(@bug_tests);
foreach my $d (@bug_tests) foreach my $d (@bug_tests)

19
qpdf/qtest/qpdf/issue-143.out Normal file
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@ -0,0 +1,19 @@
WARNING: issue-143.pdf: can't find PDF header
WARNING: issue-143.pdf (xref stream: object 3 0, file position 654): stream keyword not followed by proper line terminator
WARNING: issue-143.pdf (xref stream: object 3 0, file position 607): stream dictionary lacks /Length key
WARNING: issue-143.pdf (xref stream: object 3 0, file position 654): attempting to recover stream length
WARNING: issue-143.pdf (xref stream: object 3 0, file position 654): recovered stream length: 36
WARNING: issue-143.pdf (xref stream: object 3 0, file position 694): expected endobj
WARNING: issue-143.pdf: file is damaged
WARNING: issue-143.pdf (object 1 0, file position 48): expected n n obj
WARNING: issue-143.pdf: Attempting to reconstruct cross-reference table
WARNING: issue-143.pdf (file position 24): expected dictionary key but found non-name object; inserting key /QPDFFake1
WARNING: issue-143.pdf (file position 24): expected dictionary key but found non-name object; inserting key /QPDFFake2
WARNING: issue-143.pdf (file position 24): expected dictionary key but found non-name object; inserting key /QPDFFake3
WARNING: issue-143.pdf (file position 24): expected dictionary key but found non-name object; inserting key /QPDFFake4
WARNING: issue-143.pdf (object 1 0, file position 21): stream dictionary lacks /Length key
WARNING: issue-143.pdf (object 1 0, file position 84): attempting to recover stream length
WARNING: issue-143.pdf (object 1 0, file position 84): recovered stream length: 606
WARNING: issue-143.pdf (object 1 0, file position 694): expected endobj
WARNING: object stream 1 (file position 33): expected dictionary key but found non-name object; inserting key /QPDFFake1
qpdf: operation succeeded with warnings; resulting file may have some problems

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qpdf/qtest/qpdf/issue-143.pdf Normal file
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