43 lines
1.5 KiB
Markdown
43 lines
1.5 KiB
Markdown
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# Fuzz Testing
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Fuzz testing is:
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> An automated software testing technique that involves providing invalid, unexpected, or random data as inputs to a program.
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We use coverage guided fuzz testing to automatically discover bugs in PDF.js.
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This `fuzz/` directory contains the configuration and the fuzz tests for PDF.js.
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To generate and run fuzz tests, we use the [Jazzer.js](https://github.com/CodeIntelligenceTesting/jazzer.js/) library.
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## Running a fuzzer
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This directory contains fuzzers like for example `jpeg_image.fuzz`. You can run it with:
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Generate image decoders:
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```sh
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$ gulp image_decoders
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```
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Run fuzz target:
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```sh
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$ npx jazzer fuzz/jpeg_image.fuzz --sync
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```
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You should see output that looks something like this:
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```
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#2 INITED exec/s: 0 rss: 128Mb
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#65536 pulse corp: 1/1b lim: 652 exec/s: 32768 rss: 140Mb
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#131072 pulse corp: 1/1b lim: 1300 exec/s: 32768 rss: 140Mb
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#262144 pulse corp: 1/1b lim: 2611 exec/s: 32768 rss: 140Mb
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#524288 pulse corp: 1/1b lim: 4096 exec/s: 30840 rss: 140Mb
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#1048576 pulse corp: 1/1b lim: 4096 exec/s: 29959 rss: 140Mb
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#2097152 pulse corp: 1/1b lim: 4096 exec/s: 29537 rss: 140Mb
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```
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It will continue to generate random inputs forever, until it finds a
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bug or is terminated. The testcases for bugs it finds can be seen in
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the form of `crash-*` or `timeout-*` at the place from where command is run.
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You can rerun the fuzzer on a single input by passing it on the
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command line `npx jazzer fuzz/jpeg_image.fuzz /path/to/testcase`.
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