use uninitialized output buffers for the fuzzers #112
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bjorn3
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Jun 10, 2025
| unsafe { output.set_len(usize::try_from(total).unwrap()) }; | ||
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| // Just check that this byte is in fact initialized. | ||
| _ = output.last() == Some(&0); |
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| _ = output.last() == Some(&0); | |
| std::hint::black_box(output.last() == Some(&0)); |
otherwise it will be optimized away, which would probably cause asan to not catch uninitialized memory.
bjorn3
reviewed
Jun 10, 2025
| unsafe { output.set_len(usize::try_from(total).unwrap()) }; | ||
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| // Just check that this byte is in fact initialized. | ||
| _ = output.last() == Some(&0); |
bjorn3
approved these changes
Jun 10, 2025
we previously missed a bug in zlib-rs due to only using initialized output buffers
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Just as a note: currently the fuzzer probably won't catch uninitialized memory. For that, we'd need 1) a much more recent version of |
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we previously missed a bug in zlib-rs due to only using initialized output buffers. Now we use initialized buffers at least in some places. Because bzip2 doesn't use SIMD, it should never read from these buffers anyway. In effect we test now that the total number of bytes that was written is actually correct.
cc @ros-cr