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Only allow access to local variables and only if they have a stack size of one.

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This commit is contained in:
chriseth
2017-04-25 16:49:04 +02:00
parent f19e6a09a7
commit dfaab73efe
3 changed files with 53 additions and 63 deletions
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libsolidity/analysis/TypeChecker.cpp
+38 -28
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@@ -25,6 +25,7 @@
#include <boost/range/adaptor/reversed.hpp>
#include <libsolidity/ast/AST.h>
#include <libsolidity/inlineasm/AsmAnalysis.h>
#include <libsolidity/inlineasm/AsmData.h>
using namespace std;
using namespace dev;
@@ -637,50 +638,59 @@ bool TypeChecker::visit(InlineAssembly const& _inlineAssembly)
auto ref = _inlineAssembly.annotation().externalReferences.find(&_identifier);
if (ref == _inlineAssembly.annotation().externalReferences.end())
return size_t(-1);
size_t valueSize = size_t(-1);
Declaration const* declaration = ref->second.declaration;
solAssert(!!declaration, "");
if (auto var = dynamic_cast<VariableDeclaration const*>(declaration))
{
if (!var->isLocalVariable())
{
typeError(_identifier.location, "Only local variables are supported.");
return size_t(-1);
}
if (var->type()->dataStoredIn(DataLocation::Storage))
{
typeError(_identifier.location, "Storage reference variables are not supported.");
return size_t(-1);
}
if (var->type()->sizeOnStack() != 1)
{
typeError(_identifier.location, "Only types that use one stack slot are supported.");
return size_t(-1);
}
if (var->isConstant())
{
typeError(_identifier.location, "Constant variables not supported by inline assembly.");
return size_t(-1);
}
}
else if (_context == assembly::IdentifierContext::LValue)
{
typeError(_identifier.location, "Only local variables can be assigned to in inline assembly.");
return size_t(-1);
}
if (_context == assembly::IdentifierContext::RValue)
{
solAssert(!!declaration->type(), "Type of declaration required but not yet determined.");
if (dynamic_cast<FunctionDefinition const*>(declaration))
valueSize = 1;
else if (auto var = dynamic_cast<VariableDeclaration const*>(declaration))
{
if (var->isConstant())
fatalTypeError(SourceLocation(), "Constant variables not yet implemented for inline assembly.");
if (var->isLocalVariable())
valueSize = var->type()->sizeOnStack();
else if (!var->type()->isValueType())
valueSize = 1;
else
// We cannot use `sizeOnStack()` here because we do not insert the value
// into inline assembly but rather the storage location.
valueSize = 2; // slot number, intra slot offset
}
else if (dynamic_cast<VariableDeclaration const*>(declaration))
{
}
else if (auto contract = dynamic_cast<ContractDefinition const*>(declaration))
{
if (!contract->isLibrary())
{
typeError(_identifier.location, "Expected a library.");
return size_t(-1);
valueSize = 1;
}
}
else
return size_t(-1);
}
else
{
// lvalue context
if (auto varDecl = dynamic_cast<VariableDeclaration const*>(declaration))
{
if (!varDecl->isLocalVariable())
return size_t(-1); // only local variables are inline-assembly lvalues
valueSize = size_t(declaration->type()->sizeOnStack());
}
else
return size_t(-1);
}
ref->second.valueSize = valueSize;
return valueSize;
ref->second.valueSize = 1;
return size_t(1);
};
assembly::AsmAnalyzer::Scopes scopes;
assembly::AsmAnalyzer analyzer(scopes, m_errors, identifierAccess);