I spent the morning chasing a crash in our distributed engine. The stack trace pointed to a segfault deep inside folly::FiberManager.
gdb showed that a critical pointer was garbage: 0x676974736e6f5373.
Usually, I’d suspect a race condition or a use-after-free. I stared at the hex for a while, checking for alignment issues or bit-flips, but it just looked like random entropy.
Out of frustration, I pasted the info locals dump into Gemini 3. I didn't ask it to fix the code, I just asked: "What do you see?"
It didn't try to analyze the C++ logic. Instead, it treated the address as data. It pointed out that on an x86-64 (Little Endian) system, 0x676974736e6f5373 decodes perfectly to the ASCII string: "sSonstig".
It clicked immediately. "Sonstig" is German for "Miscellaneous".
It turns out a legacy localization function was writing the category name "Sonstiges" into a stack buffer that was too small. It overflowed and perfectly overwrote the FiberManager pointer with the bytes of the word.
I think we often focus too much on LLMs for "Code Generation" (writing boilerplate). For me, the real killer feature is Pattern Recognition in raw data. I would have stared at that hex for hours seeing only noise; the model recognized the semantic meaning in milliseconds.
Has anyone else found LLMs useful specifically for decoding raw dumps or logs like this?
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Tell HN: Gemini 3 found a stack smash in a hex dump that I missed · HackerTrans
gdb showed that a critical pointer was garbage: 0x676974736e6f5373.
Usually, I’d suspect a race condition or a use-after-free. I stared at the hex for a while, checking for alignment issues or bit-flips, but it just looked like random entropy.
Out of frustration, I pasted the info locals dump into Gemini 3. I didn't ask it to fix the code, I just asked: "What do you see?"
It didn't try to analyze the C++ logic. Instead, it treated the address as data. It pointed out that on an x86-64 (Little Endian) system, 0x676974736e6f5373 decodes perfectly to the ASCII string: "sSonstig".
It clicked immediately. "Sonstig" is German for "Miscellaneous".
It turns out a legacy localization function was writing the category name "Sonstiges" into a stack buffer that was too small. It overflowed and perfectly overwrote the FiberManager pointer with the bytes of the word.
I think we often focus too much on LLMs for "Code Generation" (writing boilerplate). For me, the real killer feature is Pattern Recognition in raw data. I would have stared at that hex for hours seeing only noise; the model recognized the semantic meaning in milliseconds.
Has anyone else found LLMs useful specifically for decoding raw dumps or logs like this?