AFL-fuzz hang/crash fixes #1886
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E.g. nix-instantiate --eval -E 'abort "\r"' hangs. Found by afl-fuzz.
Otherwise, running e.g. nix-instantiate --eval -E --strict 'builtins.replaceStrings [""] ["X"] "abc"' would just hang in an infinite loop. Found by afl-fuzz.
The assertion is broken because there is no one-to-one mapping from
length of a base64 string to the length of the output.
E.g.
"1q69lz7Empb06nzfkj651413n9icx0njmyr3xzq1j9q=" results in a 32-byte output.
"1q69lz7Empb06nzfkj651413n9icx0njmyr3xzq1j9qy" results in a 33-byte output.
To reproduce, evaluate:
builtins.derivationStrict {
name = "0";
builder = "0";
system = "0";
outputHashAlgo = "sha256";
outputHash = "1q69lz7Empb06nzfkj651413n9icx0njmyr3xzq1j9qy";
}
Found by afl-fuzz.
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Nice! Have any information on your AFL setup for Nix? Might also be fun to try on macOS due to the different codepaths we exercise. |
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This is great! Next stop.... OSS-Fuzz? |
shlevy
reviewed
Feb 20, 2018
| @@ -1216,7 +1216,7 @@ std::string filterANSIEscapes(const std::string & s, unsigned int width) | |||
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| else if (*i == '\r') | |||
| // do nothing for now | |||
| ; | |||
| i++; | |||
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Nice, would love a C++ unit testing framework to put this in.
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The fix for an infinite loop in replaceString caused an infinite loop: e2d71bd. |
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Eep. Will take a look. |
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@copumpkin The setup is at https://github.com/dezgeg/fuzz-nix. However I don't actually try to build the (potential) generated derivations, just evaluate them with |
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Fix three issues AFL found in ~30 hours.