Fix unstable valstack pointer in putprop

releases/releases.yaml

@@ -1366,3 +1366,4 @@ duktape_releases:
     - "Fix failing assert for CBOR.encode() when argument is a zero-size dynamic plain array (GH-2316, GH-2318)"
     - "Fix pointer overflow in String.prototype.startsWith/endsWith() with certain arguments (GH-2320)"
     - "Fix assertion failure and incorrect behavior in some enumeration cases involving inherited duplicate keys (GH-2322)"
+    - "Fix unstable pointer in 'putvar' which could trigger e.g. in a with(proxy) statement (GH-2323)"

src-input/duk_js_var.c

@@ -1281,6 +1281,7 @@ void duk__putvar_helper(duk_hthread *thr,
                         duk_tval *val,
                         duk_bool_t strict) {
 	duk__id_lookup_result ref;
+	duk_tval tv_tmp_val;
 	duk_tval tv_tmp_obj;
 	duk_tval tv_tmp_key;
 	duk_bool_t parents;
@@ -1298,10 +1299,13 @@ void duk__putvar_helper(duk_hthread *thr,
 	DUK_ASSERT(val != NULL);
 	/* env and act may be NULL */
 
-        DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
-        DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
+	DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
+	DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
 	DUK_ASSERT_REFCOUNT_NONZERO_TVAL(val);
 
+	DUK_TVAL_SET_TVAL(&tv_tmp_val, val);  /* Stabilize. */
+	val = NULL;
+
 	/*
 	 *  In strict mode E5 protects 'eval' and 'arguments' from being
 	 *  assigned to (or even declared anywhere).  Attempt to do so
@@ -1333,15 +1337,15 @@ void duk__putvar_helper(duk_hthread *thr,
 
 			tv_val = ref.value;
 			DUK_ASSERT(tv_val != NULL);
-			DUK_TVAL_SET_TVAL_UPDREF(thr, tv_val, val);  /* side effects */
+			DUK_TVAL_SET_TVAL_UPDREF(thr, tv_val, &tv_tmp_val);  /* side effects */
 
 			/* ref.value invalidated here */
 		} else {
 			DUK_ASSERT(ref.holder != NULL);
 
 			DUK_TVAL_SET_OBJECT(&tv_tmp_obj, ref.holder);
 			DUK_TVAL_SET_STRING(&tv_tmp_key, name);
-			(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, val, strict);
+			(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, &tv_tmp_val, strict);
 
 			/* ref.value invalidated here */
 		}
@@ -1366,7 +1370,7 @@ void duk__putvar_helper(duk_hthread *thr,
 
 	DUK_TVAL_SET_OBJECT(&tv_tmp_obj, thr->builtins[DUK_BIDX_GLOBAL]);
 	DUK_TVAL_SET_STRING(&tv_tmp_key, name);
-	(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, val, 0);  /* 0 = no throw */
+	(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, &tv_tmp_val, 0);  /* 0 = no throw */
 
 	/* NB: 'val' may be invalidated here because put_value may realloc valstack,
 	 * caller beware.

tests/ecmascript/test-bug-putvar-ptrstab-proxywith-gh2323.js

@@ -0,0 +1,20 @@
+/*===
+done
+===*/
+
+function main() {
+    var v3 = [2,2,2,2,2,2,2,2,2];
+    var v4 = v3;
+    var v5 = {constructor:String,call:String,apply:String,get:String,construct:String,defineProperty:String,has:String,preventExtensions:String};
+    v3.length = 1343;
+    var v7 = new Proxy(v4,v5);
+    with (v7) {
+        var v9 = 0;
+    }
+}
+try {
+    main();
+} catch (e) {
+    print(e.stack || e);
+}
+print('done');