Stack overflow bug
silvergasp opened this issue · comments
I found a bug in the starlark parser using the fuzzing harness in #64. I'm guessing there is some recursive parsing of unary operators and as a result, you can get a stackoverflow if you chain a bunch of unary operators. e.g. attempting to parse;
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++''
Will result in a stackoverflow. It looks like a fairly unlikely scenario, and likely won't impact usage much if at all. But I thought I'd mention it anyway :)
I took a look at this case - the issue is in ExprP::into_map_payload, which uses linear stack space in the size of the expression. I don't think there's much we can easily do to avoid that, without writing this (and probably a bunch of other traverals) as stack-free, which is a fair bit of work and more complexity, so I think we just have to accept it for now.
Going to leave this ticket for all overflows. One day we might want to harden against deep recursion in the AST, but for now I think it's considered expected.