AFLplusplus VS linux

It could be cool to see some explanation of CFG representations or GIMPLE/LLVM here. GCC/Clang can print those out as text, or just compile to that code and not go lower if you ask them to. There are some interesting things you can do with bytecode, like Rellic, AFL++, or optview2. It seems a bit reductive imo to go straight from high-level code to disassembly without at all examining any layers in between. Especially if we use something like Polygeist or CIR.

Honestly, I wouldn't bother writing your own fuzzer, and just use one of the existing solutions, like afl++. Contrary to popular belief, good fuzzers do not just generate random bytes; the way they generate data depends on a genetic algorithm based on the code paths taken by the program. AFL++ can also fuzz regular binaries that weren't instrumented, but according to the documentation it is much less effective.

Be outside the loop? At least that's how they do it in their example https://github.com/AFLplusplus/AFLplusplus/blob/stable/instrumentation/README.persistent_mode.md

I use fuzzers, as every programmer should, and do not commit unless my compiler can be fuzzed for at least 24 hours without any crashes (if I were selling the software, I'd increase that period). I use AFL++ in LTO mode and comby-decomposer with a crappy script I made to collect crash test cases. I am also interested in afl-compiler-fuzzer, but have not yet tried it. Later, I'd like to try my hand at making a test generator that reaches codegen more often (no compile errors in the random source code). I use afl-tmin to minimize test cases, but the result is always illegible without manual work, and usually has extra junk the minimizer is incapable of deleting. Something like C-Reduce would be useful here.

1: https://github.com/ArkScript-lang/Ark 2: https://github.com/AFLplusplus/AFLplusplus

Frelatage is a coverage-based Python fuzzing library which can be used to fuzz python code. The development of Frelatage was inspired by various other fuzzers, including AFL/AFL++, Atheris and PyFuzzer.The main purpose of the project is to take advantage of the best features of these fuzzers and gather them together into a new tool in order to efficiently fuzz python applications.

I personally have not gone over any books over the topic so I cannot recommend books. However, there is a popular fuzzer known as AFL++ that specifies its technical workings and has a tutorial on its usage in the documentation. You can find it here. I found using the tool helped me gain a good understanding of the topic.

With AFL++ you can even determine exactly where the fork happens:

https://github.com/AFLplusplus/AFLplusplus/blob/stable/instr...

These are a bit easier to see what's going on:

https://github.com/torvalds/linux/commit/d5cf50dafc9dd5faa1e...

https://github.com/torvalds/linux/blob/d5cf50dafc9dd5faa1e61...

Unfortunately Github doesn't have a way to render symbols for whitespace, but you can tell by selecting the spaces that the previous version had leading tabs. Linus changed it so that the tokens `default` and the number e.g. `12` are also separated by a tab. This is tricky, because the token "default" is seven characters, it will always give this added tab a width of 1 char which makes it always layout the same as if it were a space no matter if you use tab widths of 1, 2, 4, or 8.

There was also a Gentoo effort to run atop FreeBSD[0]. The challenge of course is that afaik none of the BSD kernel ABIs are considered stable. The stable interface is the BSD libc. That said, with binfmt_misc, I don't see a reason you couldn't just run (at least some) FreeBSD binaries on Linux with a thin syscall translation layer (rather something like qemu-system) and then your layer hooked via binfmt_misc. I'm not aware of anyone who has done this for FreeBSD, but prior efforts existed as alternate binfmts for SysVr4/5 ELF binaries[2]. Either way would take some elbow grease, but you *might* even be able just reuse binfmt_elf and just have a new interpreter for FreeBSD elf.

[0] https://wiki.gentoo.org/wiki/Gentoo_FreeBSD

[1] https://docs.kernel.org/admin-guide/binfmt-misc.html

[2] https://github.com/torvalds/linux/blob/master/fs/binfmt_elf....

> The original less-than check was deemed incorrect

It was only deemed incorrect because of an information leak. Not because it's a valid use-case for user space to copy smaller portions of *hwrpb into user space. https://github.com/torvalds/linux/commit/21c5977a836e399fc71...

Correct. And the combined work needs to carry the MIT license text and copyright attributions for the MIT software authors. With binary distribution it must also be overt, not hidden in some source code drop, but directly accompanying the binary.

Many people who talk about relicensing never credit the MIT developers or distribute the MIT license text. "Because it's GPL now."

I don't think that you believe that, but many developers do.

Some don't see the need for source code scans for Open Source compliance, because the license.txt says GPL, so it's GPL. Prime example is the Linux kernel. There is code under different licenses in there, but people don't even read https://github.com/torvalds/linux/blob/master/COPYING till the end ("In addition, other licenses may also apply.") and conclude it's simply GPL 2 and nothing else.

Also be aware that sublicensing is not the same as relicensing.

> Does he have something against it?

He notoriously hates GNU Emacs, yes.

https://marc.info/?m=122955159617722

https://github.com/torvalds/linux/blob/master/Documentation/...

So If we would only count code and not comments, it is only 9489 LoC Rust. Which would be about 0.03% and if we take all lines and not only LoC it would be around 0.05%

[0] https://github.com/XAMPPRocky/tokei

[1] https://github.com/torvalds/linux/commit/b401b621758e46812da...

AIUI fsync is built on futex_waitv which has been upstreamed. So this has to be more than that.

https://github.com/torvalds/linux/commit/a0eb2da92b715d0c97b...

git clone --no-checkout --depth 1 https://github.com/torvalds/linux.git $dir