PSBT seeds #91

pull Sjors wants to merge 1 commits into bitcoin-core:main from Sjors:2022/06/psbt changing 6 files +13478 −0

Sjors commented at 4:50 PM on June 30, 2022: member
I ran FUZZ=psbt src/test/fuzz/fuzz to see if I reproduce the crashes introduced in https://github.com/bitcoin/bitcoin/pull/22558/files. This was indeed the case and only took a few minutes, judging by the .log files. This resulted in 4 crash- files in my ~/bitcoin-fuzz directory.

I'm confused how to contribute the new corpus entries though. I tried running this from the qa-assets repo:
```
FUZZ=psbt ../bitcoin-fuzz/src/test/fuzz/fuzz -merge=1 -use_value_profile=1 fuzz_seed_corpus/psbt ../bitcoin-fuzz
```
The result is in this PR, but not sure if this is what's needed.
PSBT seeds 5840a1c86b
in fuzz_seed_corpus/psbt/0067ca1232c1eae3bb332138a3e57321fb1bd081:1 in 5840a1c86b
```
   0 | @@ -0,0 +1,17 @@
   1 | +// Copyright (c) 2021 The Bitcoin Core developers
```
maflcko commented at 5:01 PM on June 30, 2022:

You will need to point to the fuzz inputs dir, not the source code root

Sjors commented at 5:31 PM on June 30, 2022:

What is the "fuzz inputs dir"?

maflcko commented at 5:40 PM on June 30, 2022:

https://www.llvm.org/docs/LibFuzzer.html#corpus

https://github.com/bitcoin-core/qa-assets/blob/main/.github/PULL_REQUEST_TEMPLATE.md

Sjors commented at 5:57 PM on June 30, 2022:

I didn't use a corpus afaik, so it's not clear to me what to merge with what.

maflcko commented at 6:03 PM on June 30, 2022:

Oh, I see. You either generated fuzz inputs to a folder or kept them in memory only. Regardless, fuzz crashes are saved to the current working dir. Moreover, it won't be possible to -merge=1 crashing inputs.

If there is a fix available and you want to -merge=1 the crashes, move them to a folder first.

Sjors commented at 6:07 PM on June 30, 2022:

I basically followed the quick-start guide: https://github.com/bitcoin/bitcoin/blob/master/doc/fuzzing.md#quickstart-guide

I guess that workflow isn't suitable for contributing new entries here? (at least it would have helped catch this mistake, if running it in parallel to code review)

maflcko commented at 6:10 PM on June 30, 2022:

Yes, the quickstart guide is a guide to quickly get started, it does not reproduce the full libfuzzer documentation
maflcko commented at 12:53 PM on July 4, 2022: contributor

Are you still working on this?
Sjors commented at 1:24 PM on July 4, 2022: member

Closing for now. I don't have time atm to deepen my understanding of fuzzing beyond being able to copy-paste incantations :-)
Sjors closed this on Jul 4, 2022

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