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Comment by zetafunction | Hacker News Reader

Oilpan isn't without issues though: finalization causes quite a few headaches, implementation details like concurrent marking make it hard to support things like std::variant, and the interface between Oilpan and non-Oilpan types often introduces opportunities for unsafety.

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Indeed. It's tradeoffs, but they've been sufficient for much of the codebase for a very long time. Taking no major action (Oilpan or memory safe language) for nearly a decade was also a tradeoff. I don't think the long list of security issues there was worth it.

Hmm. The blink dirs seem to have a very large number of security issues relevant too, despite oilpan. Which is what we'd expect, honestly; oilpan does not solve all uaf problems, uafs are not all (or even the majority of) security problems, etc. The combo of "sufficient for much of the codebase" and "the long list of security issues" paints a picture of most of the codebase being secure due to oilpan, while UI code is riddled with holes due to its lack. The reality is dramatically more nuanced (as you know, but readers of your comment might not).

As a views maintainer, I'm familiar with some of the security bugs on the UI side. Clickjacking-type issues are more common there than uafs. Uafs are an issue, but the problems are not so much due to problematic use of unsafe c++ types and idioms as problematic API designs -- resulting in, for example, cases where it's not clear whether an object is expected to be able to respond safely to calls at all, whether or not it's technically alive. Oilpan, MiraclePtr, proper use of smart pointers would all help bandaid the uafs, but are in many cases difficult to apply correctly without understanding (and often fixing) the underlying systemic design problems. Which is happening, but slowly.

There are also more dimensions of tradeoffs involved, but this is long winded enough as it is. The tldr is that at this point I would consider a couple other options better uses of effort for tackling this specific problem compared to converting browser types to oilpan.

Possibly another way of expressing your point: after writing my above comment, I found myself wondering how much a system that kept these UAF pointers alive longer (to eliminate the UAFs, e.g a GC) would actually reduce the attack surface -- the UAF-ish bugs are still bugs, and code poking at a GC-preserved object that the rest of the code doesn't really expect to still be alive might itself be pretty fraught.

> the UAF-ish bugs are still bugs, and code poking at a GC-preserved object that the rest of the code doesn't really expect to still be alive might itself be pretty fraugh

For the LayoutObject heirarchy - the team doing that conversion added a NOT_DESTROYED() macro for this reason. It's gross, but was the least worst option.

As an aside - the performance of oilpan is broadly net positive now if you avoid some of the pitfalls. (The largest being a write into a Member<> requires a write-barrier). E.g. Things become trivially destructible, and no ref incrementing/decrementing, etc.

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