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We found a division by zero bug in FFmpeg with a vibecoded fuzzer

code.ffmpeg.org

201–210 of 274 posts

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#201
post #84

Earlier quoted context omitted.

Absolutely not. By most accounts they're terrible at fixing anything other than trivial bugs in complex codebases e.g. Linux kernel, but they're much better at finding them.

So you put it in a loop and tell it to find the bugs in the code it wrote. What's the issue?

What value are you providing in this scenario?

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#202

Earlier quoted context omitted.

Oddly enough I can’t access that site, it just heats up my phone solving hashes. Gave up after about a minute and anubis had only made it less than halfway through. I doubt the real bots have any trouble bypassing it.

It's puzzling how mild the reactions are to Anubis compared to the people reacting to seeing one singular Cloudflare captcha checkbox. I'd much rather a checkbox than a brief CPU-intensive hashing session.

I expect the complaints would be fewer if it was a smaller thing, or if everyone had their own version rather than it feeling like one company deciding if you should be able to use a large fraction of the internet.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#203
post #54

Earlier quoted context omitted.

A.I. is useful for this. But it would be even more useful if all new code were written in Rust or some other memory-safe language. A.I. could also be used to port C/C++ codebases to Rust, which isn't economically feasible at the moment.

I mean I get the sentiment but Rust won't save you against division by zero, it'll just panic at runtime like every other language.

The Rust standard library has `NonZero`, which, if used, at least forces you to consider what you initialize it with. Doing

  let foo = NonZero::new(unvalidated_input).unwrap();
is at the very least a big red sign that stands out in the code and should fail code review.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#204

Earlier quoted context omitted.

Oddly enough I can’t access that site, it just heats up my phone solving hashes. Gave up after about a minute and anubis had only made it less than halfway through. I doubt the real bots have any trouble bypassing it.

It's puzzling how mild the reactions are to Anubis compared to the people reacting to seeing one singular Cloudflare captcha checkbox. I'd much rather a checkbox than a brief CPU-intensive hashing session.

Cloudflare doesn't even let my browser (qutebrowser) through. Anubis will sometimes sit and ask for ridiculous amounts of work, but at least it's never outright denied access.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#205

I am sure the fuzzer is interesting. But this bug feels like something an LLM would flag as a major finding but turns out to be completely benign. Update: I tried to look into the fuzzer but it is hard to get past the AI blabb. Can someone please explain to me what it does beside being structure aware?

It crashes because of input that should have been rejected for being invalid. How could that be construed as being benign?

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#206
post #96

Earlier quoted context omitted.

Not custom. It's an existing module for a format called VPK. It's a quite trivial bug though, not exploitable apart from DOS and won't ever happen in a real file.

I thought you meant Disk Operating System until I realized you probably meant DoS

FFmpeg on DOS is enough for anybody as long as you let your 0.00066B model check the movie for 0day exploits.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#207

Earlier quoted context omitted.

I assume you're offering to pay for the increased server costs? I had some git hosting up for a while, and was serving hundreds of qps and several terabytes per month. I can only imagine want significant sites are serving.

> I assume you're offering to pay for the increased server costs? Such a non-argument. I'm expecting people to create better, more effective, and less intrusive anti-bot measures. Measures that accurately detect bots but don't exclude real people from the web simply because of the browser they're using, or the country they either appear to be in or are in fact in, for example.

I am expecting a unicorn.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#208

I am sure the fuzzer is interesting. But this bug feels like something an LLM would flag as a major finding but turns out to be completely benign. Update: I tried to look into the fuzzer but it is hard to get past the AI blabb. Can someone please explain to me what it does beside being structure aware?

It crashes because of input that should have been rejected for being invalid. How could that be construed as being benign?

afaict, decoder bugs like these are treated with lowest priority possible.

It is not enabled by default. It is used only in video games, which input files are fixed set of asset that came with the game.

It can be a crash, yes. but the typical user of this codec won't care.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#209

I am sure the fuzzer is interesting. But this bug feels like something an LLM would flag as a major finding but turns out to be completely benign. Update: I tried to look into the fuzzer but it is hard to get past the AI blabb. Can someone please explain to me what it does beside being structure aware?

It crashes because of input that should have been rejected for being invalid. How could that be construed as being benign?

Because an attacker would not gain anything he not already has. This is basically local self-DOS.

Re: We found a division by zero bug in FFmpeg with a vibecoded fuzzer

#210

Earlier quoted context omitted.

> I assume you're offering to pay for the increased server costs? Such a non-argument. I'm expecting people to create better, more effective, and less intrusive anti-bot measures. Measures that accurately detect bots but don't exclude real people from the web simply because of the browser they're using, or the country they either appear to be in or are in fact in, for example.

I am expecting a unicorn.

It's weird to me that people are pushing back on me for expecting anti-bot services to actually solve the problem they already claim to solve.
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