From 9d5007b18e41f17c395fcfc5fc0a8c8c87f4f75d Mon Sep 17 00:00:00 2001 From: van Hauser Date: Tue, 30 Jun 2020 23:34:26 +0200 Subject: Big renaming (#429) * first commit, looks good * fix ascii percentage calc * fix ascii percentage calc * modify txt configs for test * further refinement * Revert "Merge branch 'text_inputs' into dev" This reverts commit 6d9b29daca46c8912aa9ddf6c053bc8554e9e9f7, reversing changes made to 07648f75ea5ef8f03a92db0c7566da8c229dc27b. * blacklist -> ignore renaming * rename whitelist -> instrumentlist * reduce the time interval in which the secondaries sync Co-authored-by: root --- gcc_plugin/README.instrument_file.md | 73 ++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 gcc_plugin/README.instrument_file.md (limited to 'gcc_plugin/README.instrument_file.md') diff --git a/gcc_plugin/README.instrument_file.md b/gcc_plugin/README.instrument_file.md new file mode 100644 index 00000000..d0eaf6ff --- /dev/null +++ b/gcc_plugin/README.instrument_file.md @@ -0,0 +1,73 @@ +======================================== +Using afl++ with partial instrumentation +======================================== + + This file describes how you can selectively instrument only the source files + that are interesting to you using the gcc instrumentation provided by + afl++. + + Plugin by hexcoder-. + + +## 1) Description and purpose + +When building and testing complex programs where only a part of the program is +the fuzzing target, it often helps to only instrument the necessary parts of +the program, leaving the rest uninstrumented. This helps to focus the fuzzer +on the important parts of the program, avoiding undesired noise and +disturbance by uninteresting code being exercised. + +For this purpose, I have added a "partial instrumentation" support to the gcc +plugin of AFLFuzz that allows you to specify on a source file level which files +should be compiled with or without instrumentation. + + +## 2) Building the gcc plugin + +The new code is part of the existing afl++ gcc plugin in the gcc_plugin/ +subdirectory. There is nothing specifically to do :) + + +## 3) How to use the partial instrumentation mode + +In order to build with partial instrumentation, you need to build with +afl-gcc-fast and afl-g++-fast respectively. The only required change is +that you need to set the environment variable AFL_GCC_INSTRUMENT_FILE when calling +the compiler. + +The environment variable must point to a file containing all the filenames +that should be instrumented. For matching, the filename that is being compiled +must end in the filename entry contained in this instrument list (to avoid breaking +the matching when absolute paths are used during compilation). + +For example if your source tree looks like this: + +``` +project/ +project/feature_a/a1.cpp +project/feature_a/a2.cpp +project/feature_b/b1.cpp +project/feature_b/b2.cpp +``` + +and you only want to test feature_a, then create a instrument list file containing: + +``` +feature_a/a1.cpp +feature_a/a2.cpp +``` + +However if the instrument list file contains only this, it works as well: + +``` +a1.cpp +a2.cpp +``` + +but it might lead to files being unwantedly instrumented if the same filename +exists somewhere else in the project directories. + +The created instrument list file is then set to AFL_GCC_INSTRUMENT_FILE when you compile +your program. For each file that didn't match the instrument list, the compiler will +issue a warning at the end stating that no blocks were instrumented. If you +didn't intend to instrument that file, then you can safely ignore that warning. -- cgit 1.4.1