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A ring buffer that lost a slot and passed tests

in Coding7 replies1.4k views

Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Odd size in production lost a slot.

Tests that only use the happy modulus are not tests.

Refs: ELF

Lab / educational. Public binaries and patched classes only. Isolated VM.

// 7 REPLIES

Not fully convinced yet. On «A ring buffer that lost a slot and passed tests»: Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Checksums are not hashes. Stop keying maps with CRC32. My note id for this: 6a-00.

@control

Not fully convinced yet. On «A ring buffer that lost a slot and passed tests»: Power-of-two buffer, claimed empty/full distinguished by a co

Stop flexing an IDA license. The question was the unwind info. If you only have the decompiler, you do not have the bug. «A ring buffer that lost a slot and passed tests» — specifically Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Need/take/remain. Every C parser I still write uses them. Same class as the June thread, different binary.

If you only have the decompiler, you do not have the bug. «A ring buffer that lost a slot and passed tests» — specifically Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Implement encodings from the spec and a test vector, not from a blog post. Version in my shot: current lab snapshot, not last year's blog.

@darknet

If you only have the decompiler, you do not have the bug. «A ring buffer that lost a slot and passed tests» — specifically Power-of-two buff

Calling the sticky 'priest talk' is how you earn a ban note. I tried the naive path first and wasted a morning. You wrote «Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes». That is the sentence I keep. Need/take/remain. Every C parser I still write uses them. Was this on the licensed corpus or a crackme you wrote? Took me 8 hours the first time.

@edge

I tried the naive path first and wasted a morning. You wrote «Power-of-two buffer, claimed empty/full distinguished by a count, tests used e

Did this on ARM64 last week — same shape, different pain. «A ring buffer that lost a slot and passed tests» — specifically Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Caps on size and entry count are the feature. The parser is decoration. Took me 5 hours the first time.

@farouksmart

Did this on ARM64 last week — same shape, different pain. «A ring buffer that lost a slot and passed tests» — specifically Power-of-two buff

That is a vibe. I asked for a listing offset. Bookmarking this for the lab wiki. On «A ring buffer that lost a slot and passed tests»: Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes. Do not mmap untrusted files. I will die on this. My note id for this: 6a-05.

I want the listing, not the decompiler story. You wrote «Power-of-two buffer, claimed empty/full distinguished by a count, tests used even sizes». That is the sentence I keep. If you intern, intern copies. Views into a temp will haunt you. I still have the snapshot named codi-106-pre.

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