Day: February 21, 2025

This Week In Security: OpenSSH, JumbledPath, And RANsacked

February 21, 2025 by 6 Comments

OpenSSH has a newly fixed pair of vulnerabilities, and while neither of them are lighting the Internet on fire, these are each fairly important.

The central observation made by the Qualsys Threat Research Unit (TRU) was that OpenSSH contains a code paradigm that could easily contain a logic bug. It’s similar to Apple’s infamous goto fail; SSL vulnerability. The setup is this: An integer, r, is initialized to a negative value, indicating a generic error code. Multiple functions are called, with r often, but not always, set to the return value of each function. On success, that may set r to 0 to indicate no error. And when one of those functions does fail, it often runs a goto: statement that short-circuits the rest of the checks. At the end of this string of checks would be a return r; statement, using the last value of r as the result of the whole function.

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A New 8-bit CPU For C

February 21, 2025 by 53 Comments

It is easy to port C compilers to architectures that look like old minicomputers or bigger CPUs. However, as the authors of the Small Device C Compiler (SDCC) found, pushing C into a typical 8-bit CPU is challenging. Lessons learned from SDCC inspired a new 8-bit architecture, F8. This isn’t just a theoretical architecture. You can find an example Verilog implementation in the SDDC project and on GitHub. The name choice may turn out to be unfortunate as there was an F8 CPU from Fairchild back in the 1970s that apparently few people remember.

In the video from FOSDEM 2025, [Phillip Krause] provides a nice overview of the how and why of F8. While it might seem odd to create a new 8-bit CPU when you can get bigger CPUs for pennies, you have to consider that 8-bit machines are more than enough for many jobs, and if you can squeeze one into an FPGA, it might be a good choice as opposed to having to get a bigger FPGA to hold your design and a 32-bit CPU.

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Acoustic Engine Harnesses The Power Of Sound

February 21, 2025 by 29 Comments

If you think sonic booms from supersonic aircraft are a nuisance, wait until the sky is full of planes propelled by up-scaled versions of this interesting but deafening audio resonance engine.

Granted, there’s a lot of work to do before this “Sonic Ramjet” can fly even something as small as an RC plane. Creator [invalid_credentials] came up with the idea for a sound-powered engine after listening to the subwoofers on a car’s audio system shaking the paint off the body. The current design uses a pair of speaker drivers firing into 3D printed chambers, which are designed based on Fibonacci ratios to optimize resonance. When the speakers are driven with a low-frequency sine wave, the chambers focus the acoustic energy into powerful jets, producing enough thrust to propel a small wheeled test rig across a table.

It’s fair to ask the obvious question: is the engine producing thrust, or is the test model moving thanks to the vibrations caused by the sound? [invalid_credentials] appears to have thought of that, with a video showing a test driver generating a powerful jet of air. Downloads to STL files for both the large and small versions of the resonating chamber are provided, if you want to give it a try yourself. Just be careful not to annoy the neighbors too much.

Thanks to [cabbage] for the tip via [r/3Dprinting].