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LibPDF: Disallow parsing indirect values as operands

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An operation like 0 0 0 RG would have been confused for [ 0, 0 0 R ] G
This commit is contained in:
Julian Offenhäuser 2022-08-20 09:00:51 +02:00 committed by Sam Atkins
parent 04cb00dc9a
commit 65e83bed53
Notes: sideshowbarker 2024-07-17 06:58:30 +09:00 
Author: https://github.com/janso3
Commit: https://github.com/SerenityOS/serenity/commit/65e83bed53
Pull-request: https://github.com/SerenityOS/serenity/pull/14873
2 changed files with 17 additions and 5 deletions
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15
Userland/Libraries/LibPDF/Parser.cpp
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@ -53,7 +53,7 @@ String Parser::parse_comment()
return str;
}
PDFErrorOr<Value> Parser::parse_value()
PDFErrorOr<Value> Parser::parse_value(CanBeIndirectValue can_be_indirect_value)
{
parse_comment();
@ -75,8 +75,12 @@ PDFErrorOr<Value> Parser::parse_value()
return Value(false);
}
if (m_reader.matches_number())
return parse_possible_indirect_value_or_ref();
if (m_reader.matches_number()) {
if (can_be_indirect_value == CanBeIndirectValue::Yes)
return parse_possible_indirect_value_or_ref();
else
return parse_number();
}
if (m_reader.matches('/'))
return MUST(parse_name());
@ -513,7 +517,10 @@ PDFErrorOr<Vector<Operator>> Parser::parse_operators()
continue;
}
operator_args.append(TRY(parse_value()));
// Note: We disallow parsing indirect values here, since
// operations like 0 0 0 RG would confuse the parser
auto v = TRY(parse_value(CanBeIndirectValue::No));
operator_args.append(v);
}
return operators;

7
Userland/Libraries/LibPDF/Parser.h
View File

@ -38,7 +38,12 @@ public:
void move_by(size_t count) { m_reader.move_by(count); }
void move_to(size_t offset) { m_reader.move_to(offset); }
PDFErrorOr<Value> parse_value();
enum class CanBeIndirectValue {
No,
Yes
};
PDFErrorOr<Value> parse_value(CanBeIndirectValue = CanBeIndirectValue::Yes);
PDFErrorOr<Value> parse_possible_indirect_value_or_ref();
PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value(u32 index, u32 generation);
PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value();