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[libFuzzer] docs: update the examples

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285344 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany 2016-10-27 21:03:48 +00:00
parent 60923f36b5
commit cbc0087a47
1 changed files with 30 additions and 30 deletions
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docs/LibFuzzer.rst
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@ -92,9 +92,7 @@ options. Note that the libFuzzer library contains the ``main()`` function:
.. code-block:: console
svn co http://llvm.org/svn/llvm-project/llvm/trunk/lib/Fuzzer
# Alternative: get libFuzzer from a dedicated git mirror:
# git clone https://chromium.googlesource.com/chromium/llvm-project/llvm/lib/Fuzzer
svn co http://llvm.org/svn/llvm-project/llvm/trunk/lib/Fuzzer # or git clone https://chromium.googlesource.com/chromium/llvm-project/llvm/lib/Fuzzer
./Fuzzer/build.sh # Produces libFuzzer.a
Then build the fuzzing target function and the library under test using
@ -116,7 +114,7 @@ latent bugs by making incorrect behavior generate errors at runtime:
Finally, link with ``libFuzzer.a``::
clang -fsanitize-coverage=edge -fsanitize=address your_lib.cc fuzz_target.cc libFuzzer.a -o my_fuzzer
clang -fsanitize-coverage=trace-pc-guard -fsanitize=address your_lib.cc fuzz_target.cc libFuzzer.a -o my_fuzzer
Corpus
------
@ -305,14 +303,16 @@ Output
During operation the fuzzer prints information to ``stderr``, for example::
INFO: Seed: 3338750330
Loaded 1024/1211 files from corpus/
INFO: Seed: 1523017872
INFO: Loaded 1 modules (16 guards): [0x744e60, 0x744ea0),
INFO: -max_len is not provided, using 64
#0 READ units: 1211 exec/s: 0
#1211 INITED cov: 2575 bits: 8855 indir: 5 units: 830 exec/s: 1211
#1422 NEW cov: 2580 bits: 8860 indir: 5 units: 831 exec/s: 1422 L: 21 MS: 1 ShuffleBytes-
#1688 NEW cov: 2581 bits: 8865 indir: 5 units: 832 exec/s: 1688 L: 19 MS: 2 EraseByte-CrossOver-
#1734 NEW cov: 2583 bits: 8879 indir: 5 units: 833 exec/s: 1734 L: 27 MS: 3 ChangeBit-EraseByte-ShuffleBytes-
INFO: A corpus is not provided, starting from an empty corpus
#0 READ units: 1
#1 INITED cov: 3 ft: 2 corp: 1/1b exec/s: 0 rss: 24Mb
#3811 NEW cov: 4 ft: 3 corp: 2/2b exec/s: 0 rss: 25Mb L: 1 MS: 5 ChangeBit-ChangeByte-ChangeBit-ShuffleBytes-ChangeByte-
#3827 NEW cov: 5 ft: 4 corp: 3/4b exec/s: 0 rss: 25Mb L: 2 MS: 1 CopyPart-
#3963 NEW cov: 6 ft: 5 corp: 4/6b exec/s: 0 rss: 25Mb L: 2 MS: 2 ShuffleBytes-ChangeBit-
#4167 NEW cov: 7 ft: 6 corp: 5/9b exec/s: 0 rss: 25Mb L: 3 MS: 1 InsertByte-
...
The early parts of the output include information about the fuzzer options and
@ -350,19 +350,16 @@ Each output line also reports the following statistics (when non-zero):
``cov:``
Total number of code blocks or edges covered by the executing the current
corpus.
``vp:``
Size of the `value profile`_.
``bits:``
Rough measure of the number of code blocks or edges covered, and how often;
only valid if the fuzzer is run with ``-use_counters=1``.
``indir:``
Number of distinct function `caller-callee pairs`_ executed with the
current corpus; only valid if the code under test was built with
``-fsanitize-coverage=indirect-calls``.
``units:``
Number of entries in the current input corpus.
``ft:``
libFuzzer uses different signals to evaluate the code coverage:
edge coverage, edge counters, value profiles, indirect caller/callee pairs, etc.
These signals combined are called *features* (`ft:`).
``corp:``
Number of entries in the current in-memory test corpus and its size in bytes.
``exec/s:``
Number of fuzzer iterations per second.
``rss:``
Current memory consumption.
For ``NEW`` events, the output line also includes information about the mutation
operation that produced the new input:
@ -397,19 +394,22 @@ A simple function that does something interesting if it receives the input
}
EOF
# Build test_fuzzer.cc with asan and link against libFuzzer.a
clang++ -fsanitize=address -fsanitize-coverage=edge test_fuzzer.cc libFuzzer.a
clang++ -fsanitize=address -fsanitize-coverage=trace-pc-guard test_fuzzer.cc libFuzzer.a
# Run the fuzzer with no corpus.
./a.out
You should get an error pretty quickly::
#0 READ units: 1 exec/s: 0
#1 INITED cov: 3 units: 1 exec/s: 0
#2 NEW cov: 5 units: 2 exec/s: 0 L: 64 MS: 0
#19237 NEW cov: 9 units: 3 exec/s: 0 L: 64 MS: 0
#20595 NEW cov: 10 units: 4 exec/s: 0 L: 1 MS: 4 ChangeASCIIInt-ShuffleBytes-ChangeByte-CrossOver-
#34574 NEW cov: 13 units: 5 exec/s: 0 L: 2 MS: 3 ShuffleBytes-CrossOver-ChangeBit-
#34807 NEW cov: 15 units: 6 exec/s: 0 L: 3 MS: 1 CrossOver-
INFO: Seed: 1523017872
INFO: Loaded 1 modules (16 guards): [0x744e60, 0x744ea0),
INFO: -max_len is not provided, using 64
INFO: A corpus is not provided, starting from an empty corpus
#0 READ units: 1
#1 INITED cov: 3 ft: 2 corp: 1/1b exec/s: 0 rss: 24Mb
#3811 NEW cov: 4 ft: 3 corp: 2/2b exec/s: 0 rss: 25Mb L: 1 MS: 5 ChangeBit-ChangeByte-ChangeBit-ShuffleBytes-ChangeByte-
#3827 NEW cov: 5 ft: 4 corp: 3/4b exec/s: 0 rss: 25Mb L: 2 MS: 1 CopyPart-
#3963 NEW cov: 6 ft: 5 corp: 4/6b exec/s: 0 rss: 25Mb L: 2 MS: 2 ShuffleBytes-ChangeBit-
#4167 NEW cov: 7 ft: 6 corp: 5/9b exec/s: 0 rss: 25Mb L: 3 MS: 1 InsertByte-
==31511== ERROR: libFuzzer: deadly signal
...
artifact_prefix='./'; Test unit written to ./crash-b13e8756b13a00cf168300179061fb4b91fefbed