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Start checking for a few possible resource exhaustion scenarios for explorer (#2793)

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I couldn't figure out a way to actually hit a reasonable out-of-memory case once I add the maximum interpreter step count. However, the step count limit seems more important.

I've moved the todo stack limit out of function calls because there are plenty of ways to build up the todo stack without any function calls.

Fixes #2791
This commit is contained in:
Jon Ross-Perkins
2023-04-21 15:14:14 -07:00
committed by GitHub
parent f310316ef4
commit b828093c87
10 changed files with 104 additions and 19 deletions
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explorer/interpreter/interpreter.cpp
+24 -5
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@@ -40,6 +40,11 @@ using llvm::isa;
namespace Carbon {
// Limits for various overflow conditions.
static constexpr int64_t MaxTodoSize = 1e3;
static constexpr int64_t MaxStepsTaken = 1e6;
static constexpr int64_t MaxArenaAllocated = 1e9;
// Constructs an ActionStack suitable for the specified phase.
static auto MakeTodo(Phase phase, Nonnull<Heap*> heap) -> ActionStack {
switch (phase) {
@@ -185,6 +190,10 @@ class Interpreter {
Nonnull<llvm::raw_ostream*> print_stream_;
Phase phase_;
// The number of steps taken by the interpreter. Used for infinite loop
// detection.
int64_t steps_taken_ = 0;
};
//
@@ -951,10 +960,6 @@ auto Interpreter::CallFunction(const CallExpression& call,
Nonnull<const Value*> fun,
Nonnull<const Value*> arg,
ImplWitnessMap&& witnesses) -> ErrorOr<Success> {
constexpr int StackSizeLimit = 1000;
if (todo_.Count() > StackSizeLimit) {
return ProgramError(call.source_loc()) << "stack overflow";
}
if (trace_stream_->is_enabled()) {
*trace_stream_ << "calling function: " << *fun << "\n";
}
@@ -2394,6 +2399,20 @@ auto Interpreter::StepCleanUp() -> ErrorOr<Success> {
// State transition.
auto Interpreter::Step() -> ErrorOr<Success> {
// Check for various overflow conditions before stepping.
if (todo_.size() > MaxTodoSize) {
return ProgramError(SourceLocation("overflow", 1))
<< "Stack overflow: too many interpreter actions on stack";
}
if (++steps_taken_ > MaxStepsTaken) {
return ProgramError(SourceLocation("overflow", 1))
<< "Possible infinite loop: too many interpreter steps executed";
}
if (arena_->allocated() > MaxArenaAllocated) {
return ProgramError(SourceLocation("overflow", 1))
<< "Out of memory: exceeded arena allocation limit";
}
Action& act = todo_.CurrentAction();
switch (act.kind()) {
case Action::Kind::LocationAction:
@@ -2434,7 +2453,7 @@ auto Interpreter::RunAllSteps(std::unique_ptr<Action> action)
TraceState();
}
todo_.Start(std::move(action));
while (!todo_.IsEmpty()) {
while (!todo_.empty()) {
CARBON_RETURN_IF_ERROR(Step());
if (trace_stream_->is_enabled()) {
TraceState();