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[ewasm] Terminate on out-of-bounds access in EwasmInterpreter #10135

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Merged
chriseth merged 1 commit into from
Oct 29, 2020
Merged

[ewasm] Terminate on out-of-bounds access in EwasmInterpreter #10135

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85 changes: 40 additions & 45 deletions test/tools/yulInterpreter/EwasmBuiltinInterpreter.cpp
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -115,8 +115,6 @@ uint64_t popcnt(uint64_t _v)

}

using u512 = boost::multiprecision::number<boost::multiprecision::cpp_int_backend<512, 256, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void>>;

u256 EwasmBuiltinInterpreter::evalBuiltin(
YulString _functionName,
vector<Expression> const& _arguments,
Expand Down Expand Up @@ -144,14 +142,14 @@ u256 EwasmBuiltinInterpreter::evalBuiltin(
else if (fun == "datacopy")
{
// This is identical to codecopy.
if (accessMemory(_evaluatedArguments.at(0), _evaluatedArguments.at(2)))
copyZeroExtended(
m_state.memory,
m_state.code,
static_cast<size_t>(_evaluatedArguments.at(0)),
static_cast<size_t>(_evaluatedArguments.at(1) & numeric_limits<size_t>::max()),
static_cast<size_t>(_evaluatedArguments.at(2))
);
accessMemory(_evaluatedArguments.at(0), _evaluatedArguments.at(2));
copyZeroExtended(
m_state.memory,
m_state.code,
static_cast<size_t>(_evaluatedArguments.at(0)),
static_cast<size_t>(_evaluatedArguments.at(1) & numeric_limits<size_t>::max()),
static_cast<size_t>(_evaluatedArguments.at(2))
);
return 0;
}
else if (fun == "i32.drop" || fun == "i64.drop" || fun == "nop")
Expand Down Expand Up @@ -324,11 +322,11 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
{
if (arg[1] + arg[2] < arg[1] || arg[1] + arg[2] > m_state.calldata.size())
throw ExplicitlyTerminated();
if (accessMemory(arg[0], arg[2]))
copyZeroExtended(
m_state.memory, m_state.calldata,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
accessMemory(arg[0], arg[2]);
copyZeroExtended(
m_state.memory, m_state.calldata,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
return {};
}
else if (_fun == "getCallDataSize")
Expand Down Expand Up @@ -377,11 +375,11 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
}
else if (_fun == "codeCopy")
{
if (accessMemory(arg[0], arg[2]))
copyZeroExtended(
m_state.memory, m_state.code,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
accessMemory(arg[0], arg[2]);
copyZeroExtended(
m_state.memory, m_state.code,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
return 0;
}
else if (_fun == "getCodeSize")
Expand All @@ -407,12 +405,12 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
else if (_fun == "externalCodeCopy")
{
readAddress(arg[0]);
if (accessMemory(arg[1], arg[3]))
// TODO this way extcodecopy and codecopy do the same thing.
copyZeroExtended(
m_state.memory, m_state.code,
size_t(arg[1]), size_t(arg[2]), size_t(arg[3])
);
accessMemory(arg[1], arg[3]);
// TODO this way extcodecopy and codecopy do the same thing.
copyZeroExtended(
m_state.memory, m_state.code,
size_t(arg[1]), size_t(arg[2]), size_t(arg[3])
);
return 0;
}
else if (_fun == "getExternalCodeSize")
Expand Down Expand Up @@ -454,16 +452,16 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
else if (_fun == "finish")
{
bytes data;
if (accessMemory(arg[0], arg[1]))
data = readMemory(arg[0], arg[1]);
accessMemory(arg[0], arg[1]);
data = readMemory(arg[0], arg[1]);
logTrace(evmasm::Instruction::RETURN, {}, data);
throw ExplicitlyTerminated();
}
else if (_fun == "revert")
{
bytes data;
if (accessMemory(arg[0], arg[1]))
data = readMemory(arg[0], arg[1]);
accessMemory(arg[0], arg[1]);
data = readMemory(arg[0], arg[1]);
logTrace(evmasm::Instruction::REVERT, {}, data);
throw ExplicitlyTerminated();
}
Expand All @@ -473,11 +471,11 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
{
if (arg[1] + arg[2] < arg[1] || arg[1] + arg[2] > m_state.returndata.size())
throw ExplicitlyTerminated();
if (accessMemory(arg[0], arg[2]))
copyZeroExtended(
m_state.memory, m_state.calldata,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
accessMemory(arg[0], arg[2]);
copyZeroExtended(
m_state.memory, m_state.calldata,
size_t(arg[0]), size_t(arg[1]), size_t(arg[2])
);
return {};
}
else if (_fun == "selfDestruct")
Expand All @@ -494,18 +492,15 @@ u256 EwasmBuiltinInterpreter::evalEthBuiltin(string const& _fun, vector<uint64_t
return 0;
}

bool EwasmBuiltinInterpreter::accessMemory(u256 const& _offset, u256 const& _size)
void EwasmBuiltinInterpreter::accessMemory(u256 const& _offset, u256 const& _size)
{
if (((_offset + _size) >= _offset) && ((_offset + _size + 0x1f) >= (_offset + _size)))
{
u256 newSize = (_offset + _size + 0x1f) & ~u256(0x1f);
m_state.msize = max(m_state.msize, newSize);
return _size <= 0xffff;
}
else
m_state.msize = u256(-1);
// Single WebAssembly page.
// TODO: Support expansion in this interpreter.
m_state.msize = 65536;

return false;
if (((_offset + _size) < _offset) || ((_offset + _size) > m_state.msize))
// Ewasm throws out of bounds exception as opposed to the EVM.
throw ExplicitlyTerminated();
}

bytes EwasmBuiltinInterpreter::readMemory(uint64_t _offset, uint64_t _size)
Expand Down
3 changes: 1 addition & 2 deletions test/tools/yulInterpreter/EwasmBuiltinInterpreter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -91,8 +91,7 @@ class EwasmBuiltinInterpreter

/// Checks if the memory access is not too large for the interpreter and adjusts
/// msize accordingly.
/// @returns false if the amount of bytes read is lager than 0xffff
bool accessMemory(u256 const& _offset, u256 const& _size = 32);
void accessMemory(u256 const& _offset, u256 const& _size = 32);
/// @returns the memory contents at the provided address.
/// Does not adjust msize, use @a accessMemory for that
bytes readMemory(uint64_t _offset, uint64_t _size = 32);
Expand Down