Fix ContinuationStore desynchronization

src/wasm-interpreter.h

@@ -304,6 +304,13 @@ struct ContinuationStore {
 
   // Set when we are resuming execution, that is, re-winding the stack.
   bool resuming = false;
+
+  // On traps or other errors that unwind the stack, we reset the continuation
+  // store to return to a clean state ahead of further calls to exports.
+  void clear() {
+    continuations.clear();
+    resuming = false;
+  }
 };
 
 // Execute an expression
@@ -537,7 +544,7 @@ class ExpressionRunner : public OverriddenVisitor<SubType, Flow> {
 #if WASM_INTERPRETER_DEBUG
       std::cout << indent() << "clear continuations\n";
 #endif
-      continuationStore = std::make_shared<ContinuationStore>();
+      continuationStore->clear();
     }
   }
 

test/lit/exec/continuation-leak.wast

@@ -0,0 +1,26 @@
+;; RUN: wasm-opt %s -all --fuzz-exec-before --fuzz-exec-second=%s.second -q -o /dev/null 2>&1 | filecheck %s
+
+;; Check that clearing the continuation store in linked modules clears it in-place,
+;; so that continuations leaked from the primary module do not affect the second module.
+
+(module
+  (type $func_t (func))
+  (type $cont_t (cont $func_t))
+  (tag $tag)
+
+  (func $f_suspend
+    (suspend $tag)
+  )
+
+  (func $test1 (export "test1")
+    (local $c (ref $cont_t))
+    (local.set $c (cont.new $cont_t (ref.func $f_suspend)))
+    (resume $cont_t (local.get $c))
+  )
+)
+
+;; CHECK:      [fuzz-exec] export test1
+;; CHECK-NEXT: [exception thrown: unhandled suspend]
+;; CHECK:      [fuzz-exec] running second module
+;; CHECK-NEXT: [fuzz-exec] export test2
+;; CHECK-NEXT: [exception thrown: unhandled suspend]

test/lit/exec/continuation-leak.wast.second

@@ -0,0 +1,7 @@
+(module
+  (tag $tag)
+
+  (func $test2 (export "test2")
+    (suspend $tag)
+  )
+)