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LibWasm: Adjust signed integer operations to avoid UB

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Perform signed integer shifts, addition, subtraction, and rotations
using their corresponding unsigned type. Additionally, mod the right
hand side of shifts and rotations by the bit width of the integer per
the spec. This seems strange, but the spec is clear on the desired
wrapping behavior of arithmetic operations.
This commit is contained in:
Andrew Kaster
2021-07-11 17:40:15 -06:00
committed by Ali Mohammad Pur
parent d74eca78aa
commit 2af591267c
1 changed files with 17 additions and 16 deletions
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33
Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
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@@ -216,6 +216,7 @@ void BytecodeInterpreter::call_address(Configuration& configuration, FunctionAdd
auto lhs = lhs_entry.get<Value>().to<type>(); \
TRAP_IF_NOT(lhs.has_value()); \
TRAP_IF_NOT(rhs.has_value()); \
__VA_ARGS__; \
auto result = operation(lhs.value(), rhs.value()); \
dbgln_if(WASM_TRACE_DEBUG, "{}({} {}) = {}", #operation, lhs.value(), rhs.value(), result); \
configuration.stack().peek() = Value(cast(result)); \
@@ -881,11 +882,11 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
case Instructions::i32_popcnt.value():
UNARY_NUMERIC_OPERATION(i32, __builtin_popcount);
case Instructions::i32_add.value():
BINARY_NUMERIC_OPERATION(i32, +, i32);
BINARY_NUMERIC_OPERATION(u32, +, i32);
case Instructions::i32_sub.value():
BINARY_NUMERIC_OPERATION(i32, -, i32);
BINARY_NUMERIC_OPERATION(u32, -, i32);
case Instructions::i32_mul.value():
BINARY_NUMERIC_OPERATION(i32, *, i32);
BINARY_NUMERIC_OPERATION(u32, *, i32);
case Instructions::i32_divs.value():
BINARY_NUMERIC_OPERATION(i32, /, i32, TRAP_IF_NOT(!(Checked<i32>(lhs.value()) /= rhs.value()).has_overflow()));
case Instructions::i32_divu.value():
@@ -901,15 +902,15 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
case Instructions::i32_xor.value():
BINARY_NUMERIC_OPERATION(i32, ^, i32);
case Instructions::i32_shl.value():
BINARY_NUMERIC_OPERATION(i32, <<, i32);
BINARY_NUMERIC_OPERATION(u32, <<, i32, (rhs = rhs.value() % 32));
case Instructions::i32_shrs.value():
BINARY_NUMERIC_OPERATION(i32, >>, i32);
BINARY_NUMERIC_OPERATION(u32, >>, i32, (rhs = rhs.value() % 32)); // FIXME: eh, shouldn't we keep lhs as signed?
case Instructions::i32_shru.value():
BINARY_NUMERIC_OPERATION(u32, >>, i32);
BINARY_NUMERIC_OPERATION(u32, >>, i32, (rhs = rhs.value() % 32));
case Instructions::i32_rotl.value():
BINARY_PREFIX_NUMERIC_OPERATION(u32, rotl, i32);
BINARY_PREFIX_NUMERIC_OPERATION(u32, rotl, i32, (rhs = rhs.value() % 32));
case Instructions::i32_rotr.value():
BINARY_PREFIX_NUMERIC_OPERATION(u32, rotr, i32);
BINARY_PREFIX_NUMERIC_OPERATION(u32, rotr, i32, (rhs = rhs.value() % 32));
case Instructions::i64_clz.value():
UNARY_NUMERIC_OPERATION(i64, clz);
case Instructions::i64_ctz.value():
@@ -917,11 +918,11 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
case Instructions::i64_popcnt.value():
UNARY_NUMERIC_OPERATION(i64, __builtin_popcountll);
case Instructions::i64_add.value():
BINARY_NUMERIC_OPERATION(i64, +, i64);
BINARY_NUMERIC_OPERATION(u64, +, i64);
case Instructions::i64_sub.value():
BINARY_NUMERIC_OPERATION(i64, -, i64);
BINARY_NUMERIC_OPERATION(u64, -, i64);
case Instructions::i64_mul.value():
BINARY_NUMERIC_OPERATION(i64, *, i64);
BINARY_NUMERIC_OPERATION(u64, *, i64);
case Instructions::i64_divs.value():
OVF_CHECKED_BINARY_NUMERIC_OPERATION(i64, /, i64, TRAP_IF_NOT(rhs.value() != 0));
case Instructions::i64_divu.value():
@@ -937,15 +938,15 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
case Instructions::i64_xor.value():
BINARY_NUMERIC_OPERATION(i64, ^, i64);
case Instructions::i64_shl.value():
BINARY_NUMERIC_OPERATION(i64, <<, i64);
BINARY_NUMERIC_OPERATION(u64, <<, i64, (rhs = rhs.value() % 64));
case Instructions::i64_shrs.value():
BINARY_NUMERIC_OPERATION(i64, >>, i64);
BINARY_NUMERIC_OPERATION(u64, >>, i64, (rhs = rhs.value() % 64)); // FIXME: eh, shouldn't we keep lhs as signed?
case Instructions::i64_shru.value():
BINARY_NUMERIC_OPERATION(u64, >>, i64);
BINARY_NUMERIC_OPERATION(u64, >>, i64, (rhs = rhs.value() % 64));
case Instructions::i64_rotl.value():
BINARY_PREFIX_NUMERIC_OPERATION(u64, rotl, i64);
BINARY_PREFIX_NUMERIC_OPERATION(u64, rotl, i64, (rhs = rhs.value() % 64));
case Instructions::i64_rotr.value():
BINARY_PREFIX_NUMERIC_OPERATION(u64, rotr, i64);
BINARY_PREFIX_NUMERIC_OPERATION(u64, rotr, i64, (rhs = rhs.value() % 64));
case Instructions::f32_abs.value():
UNARY_NUMERIC_OPERATION(float, fabsf);
case Instructions::f32_neg.value():