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LibWasm: Limit the call stack depth and the number of executed insts

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These limits are described in the spec, and we're supposed to stop
execution at some point.
The limits are arbitrarily chosen.
This commit is contained in:
Ali Mohammad Pur 2021-06-21 21:03:08 +04:30 • committed by Ali Mohammad Pur
parent 9971d13844
commit c4b82ace74
2 changed files with 11 additions and 0 deletions
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7
Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
View file

@ -36,8 +36,13 @@ void BytecodeInterpreter::interpret(Configuration& configuration)
auto& instructions = configuration.frame().expression().instructions(); auto& instructions = configuration.frame().expression().instructions();
auto max_ip_value = InstructionPointer { instructions.size() }; auto max_ip_value = InstructionPointer { instructions.size() };
auto& current_ip_value = configuration.ip(); auto& current_ip_value = configuration.ip();
u64 executed_instructions = 0;
while (current_ip_value < max_ip_value) { while (current_ip_value < max_ip_value) {
if (executed_instructions++ >= Constants::max_allowed_executed_instructions_per_call) [[unlikely]] {
m_do_trap = true;
return;
}
auto& instruction = instructions[current_ip_value.value()]; auto& instruction = instructions[current_ip_value.value()];
auto old_ip = current_ip_value; auto old_ip = current_ip_value;
interpret(configuration, current_ip_value, instruction); interpret(configuration, current_ip_value, instruction);
@ -122,6 +127,8 @@ void BytecodeInterpreter::store_to_memory(Configuration& configuration, Instruct
void BytecodeInterpreter::call_address(Configuration& configuration, FunctionAddress address) void BytecodeInterpreter::call_address(Configuration& configuration, FunctionAddress address)
{ {
TRAP_IF_NOT(configuration.depth() <= Constants::max_allowed_call_stack_depth);
auto instance = configuration.store().get(address); auto instance = configuration.store().get(address);
TRAP_IF_NOT(instance); TRAP_IF_NOT(instance);
FunctionType const* type { nullptr }; FunctionType const* type { nullptr };

4
Userland/Libraries/LibWasm/Constants.h
View file

@ -36,4 +36,8 @@ static constexpr auto extern_global_tag = 0x03;
static constexpr auto page_size = 64 * KiB; static constexpr auto page_size = 64 * KiB;
// Limits
static constexpr auto max_allowed_call_stack_depth = 1000;
static constexpr auto max_allowed_executed_instructions_per_call = 64 * 1024 * 1024;
} }