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Detect xref pointer infinite loop (fixes #149)

This commit is contained in:
Jay Berkenbilt 2017-08-25 19:58:31 -04:00
parent 2d0c68735b
commit 85f05cc57f
5 changed files with 134 additions and 0 deletions
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5
ChangeLog
View File

@ -1,3 +1,8 @@
2017-08-25 Jay Berkenbilt <ejb@ql.org>
* Detect infinite loop while finding additional xref tables. Fixes
#149.
2017-08-22 Jay Berkenbilt <ejb@ql.org>
* 7.0.b1: release

6
libqpdf/QPDF.cc
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@ -491,8 +491,10 @@ void
QPDF::read_xref(qpdf_offset_t xref_offset)
{
std::map<int, int> free_table;
std::set<qpdf_offset_t> visited;
while (xref_offset)
{
visited.insert(xref_offset);
char buf[7];
memset(buf, 0, sizeof(buf));
this->m->file->seek(xref_offset, SEEK_SET);
@ -520,6 +522,10 @@ QPDF::read_xref(qpdf_offset_t xref_offset)
{
xref_offset = read_xrefStream(xref_offset);
}
if (visited.count(xref_offset) != 0)
{
xref_offset = 0;
}
}
if (! this->m->trailer.isInitialized())

1
qpdf/qtest/qpdf.test
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@ -221,6 +221,7 @@ my @bug_tests = (
["141a", "/W entry size 0", 2],
["141b", "/W entry size 0", 2],
["143", "self-referential ostream", 3],
["149", "xref prev pointer loop", 3],
);
$n_tests += scalar(@bug_tests);
foreach my $d (@bug_tests)

2
qpdf/qtest/qpdf/issue-149.out Normal file
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@ -0,0 +1,2 @@
WARNING: issue-149.pdf: reported number of objects (11) inconsistent with actual number of objects (7)
qpdf: operation succeeded with warnings; resulting file may have some problems

120
qpdf/qtest/qpdf/issue-149.pdf Normal file
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@ -0,0 +1,120 @@
%PDF-1.7
%Á∑·∂
% vim: set tw=76 ts=2 et :
% convert with:
% ./fixlengths < hello.txt > hello.pdf ; ./genxref hello.pdf
1 0 obj
<< /Type /Catalog
/Outlines 6 0 R
/Pages 2 0 R
>>
endobj
2 0 obj
<< /Type /Pages
/Kids [3 0 R]
/Count 1
>>
endobj
3 0 obj
<< /Type /Page
/Parent 2 0 R
/MediaBox [0 0 595.276 841.89]
/Contents 4 0 R
/Resources <<
/ProcSet [/PDF /Text]
/Font << /F1 5 0 R >>
>>
>>
endobj
4 0 obj
<< /Length 36 >>
stream
BT 80 100 Td /F1 48 Tf (foo) Tj ET
endstream
endobj
5 0 obj
<< /Type /Font
/Subtype /Type1
/Name /F1
/BaseFont /Helvetica
/Encoding /MacRomanEncoding
>>
endobj
6 0 obj
<< /Type /Outlines
/Count 0
>>
endobj
xref
0 7
0000000000 65535 f
0000000125 00000 n
0000000208 00000 n
0000000283 00000 n
0000000492 00000 n
0000000583 00000 n
0000000721 00000 n
trailer
<< /Size 7
/Prev 1516
/Root 1 0 R
>>
startxref
779%%EOF
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1 1 obj
<< /Type /Catalog
/Outlines 6 0 R
/Pages 2 1 R
>>
endobj
2 1 obj
<< /Type /Pages
/Kids [3 1 R]
/Count 1
>>
endobj
3 1 obj
<< /Type /Page
/Parent 2 1 R
/MediaBox [0 0 595.276 841.89]
/Contents 4 1 R
/Resources <<
/ProcSet [/PDF /Text]
/Font << /F1 5 0 R >>
>>
>>
endobj
4 1 obj
<< /Length 36 >>
stream
BT 80 100 Td /F1 48 Tf (bar) Tj ET
endstream
endobj
xref
1 4
0000001058 00001 n
0000001141 00001 n
0000001216 00001 n
0000001425 00001 n
trailer
<< /Size 11
/Prev 779
/Root 1 1 R
>>
startxref
1516
%%EOF