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

code.ffmpeg.org

131–140 of 274 posts

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

#131

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.

[flagged]

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.

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

#132
post #91

A patch for this was submitted in April: https://lists.ffmpeg.org/archives/list/ffmpeg-devel@ffmpeg.o... Edit: And there was discussion about this back in 2024 as well

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.

happy to report my bots have no trouble with anubis or any other pow mechanism, little bit of deno and i'm right through.

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

#135
post #4
post #2

It’s interesting how AI may both raise and lower the quality of software. It’s very easy to send an AI agent on an open-ended bug hunt, and if it wastes a bunch of time and effort and finds nothing, no big deal. Time is much more important for a human developer with a salary.

Finding the bugs with LLMs is easy. Reviewing the output, cleaning it up, and making sure it doesn't break something else is the hard part.

If finding the bugs with LLMs is easy. Then making sure it doesn't break something else is just LLMs finding no bugs. Easy.

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

#136
post #4
post #2

It’s interesting how AI may both raise and lower the quality of software. It’s very easy to send an AI agent on an open-ended bug hunt, and if it wastes a bunch of time and effort and finds nothing, no big deal. Time is much more important for a human developer with a salary.

Finding the bugs with LLMs is easy. Reviewing the output, cleaning it up, and making sure it doesn't break something else is the hard part.

That hasn’t been that bad. My real issue has been the time sink involved in following along with the maintainer and jumper through their hoops. Even after I demonstrate a flaw and a potential fix. My schedule is just so busy I need to pencil in time to deal with them.

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

#137
post #70

Earlier quoted context omitted.

No one can keep up with the volume of code AI produces. We wont stop using AI. We will use AI to check AI. Of course this is crazy, but it will also unlock pretty insane scaling and productivity and ultimately we will manage it on either end via requirements and tests.

In fairness at root this has been going on for awhile. No one can keep up with the volume of machine code that modern more abstracted codebases produce. We didn't stop using syntactic programming languages we used code to check code. Not sure it's really crazy at all. It's been an abstraction for programmers probably since we stopped soldering transistors to each other.

There is a MAJOR difference between predictable generated machine code and Russian Roulette code generator.

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

#138
post #137
post #70

Earlier quoted context omitted.

In fairness at root this has been going on for awhile. No one can keep up with the volume of machine code that modern more abstracted codebases produce. We didn't stop using syntactic programming languages we used code to check code. Not sure it's really crazy at all. It's been an abstraction for programmers probably since we stopped soldering transistors to each other.

There is a MAJOR difference between predictable generated machine code and Russian Roulette code generator.

Of course there is.

But if you don’t actually read it…

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

#139

Earlier quoted context omitted.

> it will also unlock pretty insane scaling and productivity Insane scaling of bloat, bugs, and technical debt I'd say. > We will manage it on either end via requirements and tests It is so crazy that this is being touted as a sane strategy. When I was a much worse programmer, I tried to write a big complicated string manipulation function to take two types of scripts in a language and add diacritics. I had the requi…

I'm not so sure LLM code today is below average. There was a time that things posted to dailywtf were normal everyday stuff

Sorry, no, they wouldn't have been WTF's if they were normal

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

#140
post #91

A patch for this was submitted in April: https://lists.ffmpeg.org/archives/list/ffmpeg-devel@ffmpeg.o... Edit: And there was discussion about this back in 2024 as well

For those with difficulty accessing:

- - -

From: Anthony Hurtado

vpk_read_packet() divides vpk->last_block_size and (par->block_align - vpk->last_block_size) by par->ch_layout.nb_channels without checking for zero.

While vpk_read_header() validates nb_channels > 0, the codec parameters may become zero through format probing misidentification (VPK probe score is 2/3 of AVPROBE_SCORE_MAX) or codec parameter reset, causing SIGFPE.

Fix by:

- Checking nb_channels != 0 before division in vpk_read_packet

- Returning EOF for empty last blocks (last_block_size == 0)

- Validating block_count > 0 in vpk_read_header

- Validating last_block_size Found by fuzzing with libFuzzer + AddressSanitizer. Reproduces with 10 distinct inputs.

[patch redacted for brevity]

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