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I work on SpiderMonkey, so I mostly looked at the JS bugs. It was a smorgasbord of various things. Broadly speaking I'd say the most impressive bugs were TOCTOU issues, where we checked something and later acted on it, and the testcase found a clever way to invalidate the result of the check in between.

If you look closely at, say, this patch, you might get a sense of what I mean (although the real cleverness is in the testcase, which we have not made public): https://hg-edge.mozilla.org/integration/autoland/rev/c29515d...

by nh21 hours ago|

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Given the commit is 4 weeks old, will it eventually get comments?

The code before the patch does not look obviously wrong. Now, some more lines were added, but would you now say it now looks less obviously wrong, or more obviously correct?

It seems that the invariants needed here are either in some person's heads, or in some document that is not referenced.

Reading the code for the first time, the immediate question is: "What other lines might be missing? How can I figure?"

If the "obviously correct" level of the code does not increase for a human reviewer, how is it ensured that a similar problem will not arise in the future? Or do we need more LLM to tell us which other lines need to be added?

by reisse12 hours ago|

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> although the real cleverness is in the testcase, which we have not made public

What is the point of keeping it private? I'd bet feeding this patch to Opus and asking to look for specific TOCTOU issue fixed by the patch will make it come up with a testcase sooner or later.

by IainIreland11 hours ago|

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The same is also true of a good security researcher, and has been for a long time. The question is mostly whether it takes long enough to come up with a testcase that we've managed to ship the fix to all affected releases, and given people some time to update. (And maybe LLMs do change the calculus there! We'll have to wait and see.)

by mccr811 hours ago|

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Possibly! One of the many areas that might need rethinking in the age of AI (that started in February of this year) is how long security bugs should be hidden. We live in interesting times.

by paulvnickerson12 hours ago|

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Very cool, thank you.

by mccr811 hours ago|

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I'd say it leans towards memory corruption kinds of issues, as those are easiest to pass the validator, thanks to AddressSanitizer. I think there's a lot of potential for making the validator more sophisticated. Like maybe you add a JS function that will only crash when run in the parent process and have a validator that checks for that specific crash, as a way for the LLM to "prove" that it managed to run arbitrary JS in the parent. Would that turn up subtler issues? Maybe.