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Merge pull request #1241 from m-holger/fuzz

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Add further sanity checks to QPDF::reconstruct_xref
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m-holger 2024-07-14 23:40:29 +01:00 committed by GitHub
commit 01353e114f
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1 changed files with 14 additions and 9 deletions
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libqpdf/QPDF.cc
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@ -546,6 +546,11 @@ QPDF::reconstruct_xref(QPDFExc& e)
// If recovery generates more than 1000 warnings, the file is so severely damaged that there
// probably is no point trying to continue.
const auto max_warnings = m->warnings.size() + 1000U;
auto check_warnings = [this, max_warnings]() {
if (m->warnings.size() > max_warnings) {
throw damagedPDF("", 0, "too many errors while reconstructing cross-reference table");
}
};
m->reconstructed_xref = true;
// We may find more objects, which may contain dangling references.
@ -600,9 +605,7 @@ QPDF::reconstruct_xref(QPDFExc& e)
setTrailer(t);
}
}
if (m->warnings.size() > max_warnings) {
throw damagedPDF("", 0, "too many errors while reconstructing cross-reference table");
}
check_warnings();
m->file->seek(next_line_start, SEEK_SET);
line_start = next_line_start;
}
@ -629,10 +632,7 @@ QPDF::reconstruct_xref(QPDFExc& e)
max_offset = offset;
setTrailer(oh.getDict());
}
if (m->warnings.size() > max_warnings) {
throw damagedPDF(
"", 0, "too many errors while reconstructing cross-reference table");
}
check_warnings();
}
if (max_offset > 0) {
try {
@ -657,8 +657,13 @@ QPDF::reconstruct_xref(QPDFExc& e)
// creating QPDF objects from JSON.
throw damagedPDF("", 0, "unable to find objects while recovering damaged file");
}
if (m->warnings.size() > max_warnings) {
throw damagedPDF("", 0, "too many errors while reconstructing cross-reference table");
check_warnings();
if (!m->parsed) {
getAllPages();
check_warnings();
if (m->all_pages.empty()) {
throw damagedPDF("", 0, "unable to find any pages while recovering damaged file");
}
}
// We could iterate through the objects looking for streams and try to find objects inside of
// them, but it's probably not worth the trouble. Acrobat can't recover files with any errors