MarcoFalke 505b4eda55
Merge #19140: tests: Avoid fuzzer-specific nullptr dereference in libevent when handling PROXY requests
20d31bdd92cc2ad9b8d26ed80da73bbcd6016144 tests: Avoid fuzzer-specific nullptr dereference in libevent when handling PROXY requests (practicalswift)

Pull request description:

  Avoid constructing requests that will be interpreted by libevent as PROXY requests to avoid triggering a `nullptr` dereference. Split out from #19074 as suggested by MarcoFalke.

  The dereference (`req->evcon->http_server`) takes place in `evhttp_parse_request_line` and is a consequence of our hacky but necessary use of the internal function `evhttp_parse_firstline_` in the `http_request` fuzzing harness.

  The suggested workaround is not aesthetically pleasing, but it successfully avoids the troublesome code path.

  `" http:// HTTP/1.1\n"` was a crashing input prior to this workaround.

  Before this PR:

  ```
  $ echo " http:// HTTP/1.1" > input
  $ src/test/fuzz/http_request input
  src/test/fuzz/http_request: Running 1 inputs 1 time(s) each.
  Running: input
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==27905==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000108 (pc 0x55a169b7e053 bp 0x7ffd452f1160 sp 0x7ffd452f10e0 T0)
  ==27905==The signal is caused by a READ memory access.
  ==27905==Hint: address points to the zero page.
      #0 0x55a169b7e053 in evhttp_parse_request_line depends/work/build/x86_64-pc-linux-gnu/libevent/2.1.11-stable-36daee64dc1/http.c:1883:37
      #1 0x55a169b7d9ae in evhttp_parse_firstline_ depends/work/build/x86_64-pc-linux-gnu/libevent/2.1.11-stable-36daee64dc1/http.c:2041:7
      #2 0x55a1687f624e in test_one_input(std::vector<unsigned char, std::allocator<unsigned char> > const&) src/test/fuzz/http_request.cpp:51:9
  …
  $ echo $?
  1
  ```

  After this PR:

  ```
  $ echo " http:// HTTP/1.1" > input
  $ src/test/fuzz/http_request input
  src/test/fuzz/http_request: Running 1 inputs 1 time(s) each.
  Running: input
  Executed input in 0 ms
  ***
  *** NOTE: fuzzing was not performed, you have only
  ***       executed the target code on a fixed set of inputs.
  ***
  $ echo $?
  0
  ```

  See [`doc/fuzzing.md`](https://github.com/bitcoin/bitcoin/blob/master/doc/fuzzing.md) for information on how to fuzz Bitcoin Core. Don't forget to contribute any coverage increasing inputs you find to the [Bitcoin Core fuzzing corpus repo](https://github.com/bitcoin-core/qa-assets).

  Happy fuzzing :)

Top commit has no ACKs.

Tree-SHA512: 7a6b68e52cbcd6c117487e74e47760fe03566bec09b0bb606afb3b652edfd22186ab8244e8e27c38cef3fd0d4a6c237fe68b2fd22e0970c349e4ab370cf3e304
2020-07-10 22:51:56 +02:00
..
2020-04-16 13:33:09 -04:00
2020-03-31 17:11:47 -04:00

Unit tests

The sources in this directory are unit test cases. Boost includes a unit testing framework, and since Bitcoin Core already uses Boost, it makes sense to simply use this framework rather than require developers to configure some other framework (we want as few impediments to creating unit tests as possible).

The build system is set up to compile an executable called test_bitcoin that runs all of the unit tests. The main source file for the test library is found in util/setup_common.cpp.

Compiling/running unit tests

Unit tests will be automatically compiled if dependencies were met in ./configure and tests weren't explicitly disabled.

After configuring, they can be run with make check.

To run the unit tests manually, launch src/test/test_bitcoin. To recompile after a test file was modified, run make and then run the test again. If you modify a non-test file, use make -C src/test to recompile only what's needed to run the unit tests.

To add more unit tests, add BOOST_AUTO_TEST_CASE functions to the existing .cpp files in the test/ directory or add new .cpp files that implement new BOOST_AUTO_TEST_SUITE sections.

To run the GUI unit tests manually, launch src/qt/test/test_bitcoin-qt

To add more GUI unit tests, add them to the src/qt/test/ directory and the src/qt/test/test_main.cpp file.

Running individual tests

test_bitcoin has some built-in command-line arguments; for example, to run just the getarg_tests verbosely:

test_bitcoin --log_level=all --run_test=getarg_tests -- DEBUG_LOG_OUT

log_level controls the verbosity of the test framework, which logs when a test case is entered, for example. The DEBUG_LOG_OUT after the two dashes redirects the debug log, which would normally go to a file in the test datadir (BasicTestingSetup::m_path_root), to the standard terminal output.

... or to run just the doubledash test:

test_bitcoin --run_test=getarg_tests/doubledash

Run test_bitcoin --help for the full list.

Adding test cases

To add a new unit test file to our test suite you need to add the file to src/Makefile.test.include. The pattern is to create one test file for each class or source file for which you want to create unit tests. The file naming convention is <source_filename>_tests.cpp and such files should wrap their tests in a test suite called <source_filename>_tests. For an example of this pattern, see uint256_tests.cpp.

Logging and debugging in unit tests

make check will write to a log file foo_tests.cpp.log and display this file on failure. For running individual tests verbosely, refer to the section above.

To write to logs from unit tests you need to use specific message methods provided by Boost. The simplest is BOOST_TEST_MESSAGE.

For debugging you can launch the test_bitcoin executable with gdbor lldb and start debugging, just like you would with any other program:

gdb src/test/test_bitcoin