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Fix fuzz issue 16953 (overflow checking in xref stream index)

This commit is contained in:
Jay Berkenbilt 2019-09-17 19:48:27 -04:00
parent 17d431dfd5
commit bb83e65193
2 changed files with 12 additions and 1 deletions
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1
fuzz/qpdf_extra/16953.fuzz Normal file
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@ -0,0 +1 @@
5 0 obj<</DecodeParms<</Columns 4/Predictor 12>>/Filter/Fl/Index[2147483641 13]/Size 0/Type/XRef/W[1 2 1]>>stream hÞbd`²D endstream startxref 6

12
libqpdf/QPDF.cc
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@ -5,6 +5,7 @@
#include <map>
#include <algorithm>
#include <limits>
#include <sstream>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
@ -1202,7 +1203,16 @@ QPDF::processXRefStream(qpdf_offset_t xref_offset, QPDFObjectHandle& xref_obj)
// based on /Index. The generation number is 0 unless this is
// an uncompressed object record, in which case the generation
// number appears as the third field.
int obj = toI(indx.at(cur_chunk)) + chunk_count;
int obj = toI(indx.at(cur_chunk));
if ((std::numeric_limits<int>::max() - obj) < chunk_count)
{
std::ostringstream msg;
msg << "adding " << chunk_count << " to " << obj
<< " while computing index in xref stream would cause"
<< " an integer overflow";
throw std::range_error(msg.str());
}
obj += chunk_count;
++chunk_count;
if (chunk_count >= indx.at(cur_chunk + 1))
{