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Add a recursion limit for the interpreter's expression runner #2160

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Merged
kripken merged 1 commit into from
Jun 4, 2019
Merged

Add a recursion limit for the interpreter's expression runner #2160

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13 changes: 11 additions & 2 deletions src/wasm-interpreter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ using namespace cashew;

extern Name WASM, RETURN_FLOW;

enum { maxCallDepth = 250 };
enum { maxInterpreterDepth = 250 };

// Stuff that flows around during executing expressions: a literal, or a change
// in control flow.
Expand Down Expand Up @@ -128,8 +128,16 @@ class Indenter {
// Execute an expression
template<typename SubType>
class ExpressionRunner : public OverriddenVisitor<SubType, Flow> {
protected:
// Keep a record of call depth, to guard against excessive recursion.
size_t depth = 0;

public:
Flow visit(Expression* curr) {
depth++;
if (depth > maxInterpreterDepth) {
trap("interpreter recursion limit");
}
auto ret = OverriddenVisitor<SubType, Flow>::visit(curr);
if (!ret.breaking() &&
(isConcreteType(curr->type) || isConcreteType(ret.value.type))) {
Expand All @@ -142,6 +150,7 @@ class ExpressionRunner : public OverriddenVisitor<SubType, Flow> {
#endif
assert(ret.value.type == curr->type);
}
depth--;
return ret;
}

Expand Down Expand Up @@ -1790,7 +1799,7 @@ template<typename GlobalManager, typename SubType> class ModuleInstanceBase {
// Internal function call. Must be public so that callTable implementations
// can use it (refactor?)
Literal callFunctionInternal(Name name, const LiteralList& arguments) {
if (callDepth > maxCallDepth) {
if (callDepth > maxInterpreterDepth) {
externalInterface->trap("stack limit");
}
auto previousCallDepth = callDepth;
Expand Down