SmartSyntaxInterpreterPlugin code generation issue

> On Dec 17, 2018, at 5:37 AM, Levente Uzonyi <[hidden email]> wrote:
>
> Hi All,
>
> I found a bug in SocketPlugin which will crash the VM when triggered. While tracking the bug down, I found that SocketPlugin is a subclass of SmartSyntaxInterpreterPlugin and the cause of the bug is flawed code generation.
>
> This line of smalltalk code (from SocketPlugin >> #primitiveSocket:connectTo:port:)
>
>    self primitive: 'primitiveSocketConnectToPort' parameters: #(#Oop #ByteArray #SmallInteger ).
>
> is translated to[1]
>
>    socket = stackValue(2);
>    success(isBytes(stackValue(1)));
>    address = ((char *) (firstIndexableField(stackValue(1))));
>    port = stackIntegerValue(0);
>    if (failed()) {
>        return null;
>    }
>
> The problem here is that the code checks if stackValue(1) is a bytes object, but the result of the check is only used after all arguments are read and converted.
> So even if the second argument is not a bytes, the third line of the snipper above will treat is as a bytes object and firstIndexableField will cause segmentation fault.
>
> I presume that other SmartSyntaxInterpreterPlugins have the same argument
> validation issues, so it would be best if the code generator were fixed.