diff options
| -rw-r--r-- | TODO.md | 3 | ||||
| -rw-r--r-- | docs/Changelog.md | 1 | ||||
| -rw-r--r-- | docs/env_variables.md | 3 | ||||
| -rw-r--r-- | docs/fuzzing_in_depth.md | 4 | ||||
| -rw-r--r-- | include/envs.h | 1 | ||||
| -rw-r--r-- | instrumentation/README.llvm.md | 4 | ||||
| -rw-r--r-- | instrumentation/SanitizerCoverageLTO.so.cc | 11 | ||||
| -rw-r--r-- | instrumentation/afl-llvm-dict2file.so.cc | 17 | ||||
| -rw-r--r-- | src/afl-cc.c | 5 |
9 files changed, 41 insertions, 8 deletions
diff --git a/TODO.md b/TODO.md index 862224f0..187fa191 100644 --- a/TODO.md +++ b/TODO.md @@ -9,13 +9,12 @@ - afl-plot to support multiple plot_data - parallel builds for source-only targets - get rid of check_binary, replace with more forkserver communication - - first fuzzer should be a main automatically + - first fuzzer should be a main automatically? not sure. ## Maybe - forkserver tells afl-fuzz if cmplog is supported and if so enable it by default, with AFL_CMPLOG_NO=1 (?) set to skip? - - afl_custom_fuzz_splice_optin() - afl_custom_splice() - cmdline option from-to range for mutations diff --git a/docs/Changelog.md b/docs/Changelog.md index eee88a51..89c37912 100644 --- a/docs/Changelog.md +++ b/docs/Changelog.md @@ -10,6 +10,7 @@ - add CFI sanitizer variant to gcc targets - llvm 16 support (thanks to @devnexen!) - support llvm 15 native pcguard changes + - LTO autoken and llvm_mode: added AFL_LLVM_DICT2FILE_NO_MAIN support - better sanitizer default options support for all tools - unicorn_mode: updated and minor issues fixed - frida_mode: fix issue on MacOS diff --git a/docs/env_variables.md b/docs/env_variables.md index 0a57d190..61fb1e2b 100644 --- a/docs/env_variables.md +++ b/docs/env_variables.md @@ -129,6 +129,9 @@ subset of the settings discussed in section 1, with the exception of: write all constant string comparisons to this file to be used later with afl-fuzz' `-x` option. + - An option to `AFL_LLVM_DICT2FILE` is `AFL_LLVM_DICT2FILE_NO_MAIN=1` which + skill not parse `main()`. + - `TMPDIR` and `AFL_KEEP_ASSEMBLY`, since no temporary assembly files are created. diff --git a/docs/fuzzing_in_depth.md b/docs/fuzzing_in_depth.md index 87f31a58..efab0633 100644 --- a/docs/fuzzing_in_depth.md +++ b/docs/fuzzing_in_depth.md @@ -534,6 +534,8 @@ dictionaries/FORMAT.dict`. * With `afl-clang-fast`, you can set `AFL_LLVM_DICT2FILE=/full/path/to/new/file.dic` to automatically generate a dictionary during target compilation. + Adding `AFL_LLVM_DICT2FILE_NO_MAIN=1` to not parse main (usually command line + parameter parsing) is often a good idea too. * You also have the option to generate a dictionary yourself during an independent run of the target, see [utils/libtokencap/README.md](../utils/libtokencap/README.md). @@ -935,7 +937,7 @@ phase and start fuzzing at once. 3. Also randomize the afl-fuzz runtime options, e.g.: * 65% for `AFL_DISABLE_TRIM` * 50% for `AFL_KEEP_TIMEOUTS` - * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` + * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` + `AFL_LLVM_DICT2FILE_NO_MAIN=1` * 40% use MOpt (`-L 0`) * 40% for `AFL_EXPAND_HAVOC_NOW` * 20% for old queue processing (`-Z`) diff --git a/include/envs.h b/include/envs.h index 0770f94d..5018b0f8 100644 --- a/include/envs.h +++ b/include/envs.h @@ -133,6 +133,7 @@ static char *afl_environment_variables[] = { "AFL_LLVM_CTX", "AFL_LLVM_CTX_K", "AFL_LLVM_DICT2FILE", + "AFL_LLVM_DICT2FILE_NO_MAIN", "AFL_LLVM_DOCUMENT_IDS", "AFL_LLVM_INSTRIM_LOOPHEAD", "AFL_LLVM_INSTRUMENT", diff --git a/instrumentation/README.llvm.md b/instrumentation/README.llvm.md index 9da1b0f6..c0677474 100644 --- a/instrumentation/README.llvm.md +++ b/instrumentation/README.llvm.md @@ -167,6 +167,10 @@ Just specify `AFL_LLVM_DICT2FILE=/absolute/path/file.txt` and during compilation all constant string compare parameters will be written to this file to be used with afl-fuzz' `-x` option. +Adding `AFL_LLVM_DICT2FILE_NO_MAIN=1` will skip parsing `main()` which often +does command line parsing which has string comparisons that are not helpful +for fuzzing. + ## 6) AFL++ Context Sensitive Branch Coverage ### What is this? diff --git a/instrumentation/SanitizerCoverageLTO.so.cc b/instrumentation/SanitizerCoverageLTO.so.cc index 231151f5..f82224ed 100644 --- a/instrumentation/SanitizerCoverageLTO.so.cc +++ b/instrumentation/SanitizerCoverageLTO.so.cc @@ -236,6 +236,7 @@ class ModuleSanitizerCoverageLTO // const SpecialCaseList * Allowlist; // const SpecialCaseList * Blocklist; uint32_t autodictionary = 1; + uint32_t autodictionary_no_main = 0; uint32_t inst = 0; uint32_t afl_global_id = 0; uint32_t unhandled = 0; @@ -411,7 +412,8 @@ bool ModuleSanitizerCoverageLTO::instrumentModule( /* Show a banner */ setvbuf(stdout, NULL, _IONBF, 0); - if (getenv("AFL_DEBUG")) debug = 1; + if (getenv("AFL_DEBUG")) { debug = 1; } + if (getenv("AFL_LLVM_DICT2FILE_NO_MAIN")) { autodictionary_no_main = 1; } if ((isatty(2) && !getenv("AFL_QUIET")) || debug) { @@ -503,6 +505,13 @@ bool ModuleSanitizerCoverageLTO::instrumentModule( if (!isInInstrumentList(&F, MNAME) || !F.size()) { continue; } + if (autodictionary_no_main && + (!F.getName().compare("main") || !F.getName().compare("_main"))) { + + continue; + + } + for (auto &BB : F) { for (auto &IN : BB) { diff --git a/instrumentation/afl-llvm-dict2file.so.cc b/instrumentation/afl-llvm-dict2file.so.cc index bbbbe32c..97f1d47f 100644 --- a/instrumentation/afl-llvm-dict2file.so.cc +++ b/instrumentation/afl-llvm-dict2file.so.cc @@ -182,7 +182,7 @@ bool AFLdict2filePass::runOnModule(Module &M) { DenseMap<Value *, std::string *> valueMap; char *ptr; - int found = 0; + int found = 0, handle_main = 1; /* Show a banner */ setvbuf(stdout, NULL, _IONBF, 0); @@ -192,10 +192,14 @@ bool AFLdict2filePass::runOnModule(Module &M) { SAYF(cCYA "afl-llvm-dict2file" VERSION cRST " by Marc \"vanHauser\" Heuse <mh@mh-sec.de>\n"); - } else + } else { be_quiet = 1; + } + + if (getenv("AFL_LLVM_DICT2FILE_NO_MAIN")) { handle_main = 0; } + scanForDangerousFunctions(&M); ptr = getenv("AFL_LLVM_DICT2FILE"); @@ -210,7 +214,14 @@ bool AFLdict2filePass::runOnModule(Module &M) { for (auto &F : M) { - if (isIgnoreFunction(&F)) continue; + if (!handle_main && + (!F.getName().compare("main") || !F.getName().compare("_main"))) { + + continue; + + } + + if (isIgnoreFunction(&F)) { continue; } if (!isInInstrumentList(&F, MNAME) || !F.size()) { continue; } /* Some implementation notes. diff --git a/src/afl-cc.c b/src/afl-cc.c index 7c3682fb..7b059d40 100644 --- a/src/afl-cc.c +++ b/src/afl-cc.c @@ -2041,6 +2041,8 @@ int main(int argc, char **argv, char **envp) { " AFL_LLVM_DICT2FILE: generate an afl dictionary based on found " "comparisons\n" + " AFL_LLVM_DICT2FILE_NO_MAIN: skip parsing main() for the " + "dictionary\n" " AFL_LLVM_LAF_ALL: enables all LAF splits/transforms\n" " AFL_LLVM_LAF_SPLIT_COMPARES: enable cascaded comparisons\n" " AFL_LLVM_LAF_SPLIT_COMPARES_BITW: size limit (default 8)\n" @@ -2128,7 +2130,8 @@ int main(int argc, char **argv, char **envp) { "defaults.\n" "Recommended is afl-clang-lto with AFL_LLVM_CMPLOG or afl-clang-fast " "with\n" - "AFL_LLVM_CMPLOG and AFL_LLVM_DICT2FILE.\n\n"); + "AFL_LLVM_CMPLOG and " + "AFL_LLVM_DICT2FILE+AFL_LLVM_DICT2FILE_NO_MAIN.\n\n"); exit(1); |