diff options
Diffstat (limited to 'docs/fuzzing_in_depth.md')
| -rw-r--r-- | docs/fuzzing_in_depth.md | 42 |
1 files changed, 25 insertions, 17 deletions
diff --git a/docs/fuzzing_in_depth.md b/docs/fuzzing_in_depth.md index f75ca5dc..82437807 100644 --- a/docs/fuzzing_in_depth.md +++ b/docs/fuzzing_in_depth.md @@ -599,32 +599,40 @@ during fuzzing) and their number, a value between 50-500MB is recommended. You can set the cache size (in MB) by setting the environment variable `AFL_TESTCACHE_SIZE`. -There should be one main fuzzer (`-M main-$HOSTNAME` option) and as many -secondary fuzzers (e.g., `-S variant1`) as you have cores that you use. Every -`-M`/`-S` entry needs a unique name (that can be whatever), however, the same -`-o` output directory location has to be used for all instances. +There should be one main fuzzer (`-M main-$HOSTNAME` option - set also +`AFL_FINAL_SYNC=1`) and as many secondary fuzzers (e.g., `-S variant1`) as you +have cores that you use. Every `-M`/`-S` entry needs a unique name (that can be +whatever), however, the same `-o` output directory location has to be used for +all instances. For every secondary fuzzer there should be a variation, e.g.: -* one should fuzz the target that was compiled differently: with sanitizers - activated (`export AFL_USE_ASAN=1 ; export AFL_USE_UBSAN=1 ; export - AFL_USE_CFISAN=1`) +* one should fuzz the target that was compiled with sanitizers activated + (`export AFL_USE_ASAN=1 ; export AFL_USE_UBSAN=1 ; export AFL_USE_CFISAN=1`) * one or two should fuzz the target with CMPLOG/redqueen (see above), at least - one cmplog instance should follow transformations (`-l AT`) + one cmplog instance should follow transformations (`-l 2AT`) * one to three fuzzers should fuzz a target compiled with laf-intel/COMPCOV (see above). Important note: If you run more than one laf-intel/COMPCOV fuzzer and you want them to share their intermediate results, the main fuzzer (`-M`) must - be one of them! (Although this is not really recommended.) - -All other secondaries should be used like this: -* a quarter to a third with the MOpt mutator enabled: `-L 0` -* run with a different power schedule, recommended are: `fast` (default), + be one of them (although this is not really recommended). + +The other secondaries should be run like this: +* 10% with the MOpt mutator enabled: `-L 0` +* 10% should use the old queue cycling with `-Z` +* 50-70% should run with `AFL_DISABLE_TRIM` +* 40% should run with `-P explore` and 20% with `-P exploit` +* If you use `-a` then set 30% of the instances to not use `-a`; if you did + not set `-a` (why??), then set 30% to `-a ascii` and 30% to `-a binary`. +* run each with a different power schedule, recommended are: `fast` (default), `explore`, `coe`, `lin`, `quad`, `exploit`, and `rare` which you can set with the `-p` option, e.g., `-p explore`. See the [FAQ](FAQ.md#what-are-power-schedules) for details. -* a few instances should use the old queue cycling with `-Z` + +It can be useful to set `AFL_IGNORE_SEED_PROBLEMS=1` to skip over seeds that +crash or timeout during startup. Also, it is recommended to set `export AFL_IMPORT_FIRST=1` to load test cases -from other fuzzers in the campaign first. +from other fuzzers in the campaign first. But note that can slow down the start +of the first fuzz by quite a lot of you have many fuzzers and/or many seeds. If you have a large corpus, a corpus from a previous run or are fuzzing in a CI, then also set `export AFL_CMPLOG_ONLY_NEW=1` and `export AFL_FAST_CAL=1`. @@ -940,7 +948,7 @@ too long for your overall available fuzz run time. * 65% for `AFL_DISABLE_TRIM` * 50% for `AFL_KEEP_TIMEOUTS` * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` + `AFL_LLVM_DICT2FILE_NO_MAIN=1` - * 40% use MOpt (`-L 0`) + * 10% use MOpt (`-L 0`) * 40% for `AFL_EXPAND_HAVOC_NOW` * 20% for old queue processing (`-Z`) * for CMPLOG targets, 70% for `-l 2`, 10% for `-l 3`, 20% for `-l 2AT` @@ -950,7 +958,7 @@ too long for your overall available fuzz run time. campaign but not good for short CI runs. How this can look like can, e.g., be seen at AFL++'s setup in Google's -[oss-fuzz](https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-builder/compile_afl) +[previous oss-fuzz version](https://github.com/google/oss-fuzz/blob/3e2c5312417d1a6f9564472f3df1fd27759b289d/infra/base-images/base-builder/compile_afl) and [clusterfuzz](https://github.com/google/clusterfuzz/blob/master/src/clusterfuzz/_internal/bot/fuzzers/afl/launcher.py). |