Fix structure and formatting
MODIFY
docs/features.md
docs/features.md
@@ -4,8 +4,10 @@ AFL++ supports llvm from 3.8 up to version 12, very fast binary fuzzing with
QEMU 5.1 with laf-intel and redqueen, FRIDA mode, unicorn mode, gcc plugin, full
*BSD, Mac OS, Solaris and Android support and much, much, much more.
+## Features and instrumentation
+
| Feature/Instrumentation | afl-gcc | llvm | gcc_plugin | FRIDA mode(9) | QEMU mode(10) | unicorn_mode(10) | nyx_mode(12) | coresight_mode(11) |
-| ------------------------------|:-------:|:---------:|:----------:|:----------------:|:----------------:|:----------------:|:----------:|:----------------:|
+| ------------------------------|:--------:|:---------:|:----------:|:--------------:|:----------------:|:----------------:|:------------:|:------------------:|
| Threadsafe counters [A] | | x(3) | | | | | x | |
| NeverZero [B] | x86[_64] | x(1) | x | x | x | x | | |
| Persistent Mode [C] | | x | x | x86[_64]/arm64 | x86[_64]/arm[64] | x | | |
@@ -16,55 +18,71 @@ QEMU 5.1 with laf-intel and redqueen, FRIDA mode, unicorn mode, gcc plugin, full
| Ngram prev_loc Coverage [H] | | x(6) | | | | | | |
| Context Coverage [I] | | x(6) | | | | | | |
| Auto Dictionary [J] | | x(7) | | | | | | |
-| Snapshot Support (K) | | (x)(8) | (x)(8) | | (x)(5) | | x | |
+| Snapshot Support [K] | | (x)(8) | (x)(8) | | (x)(5) | | x | |
| Shared Memory Test cases [L] | | x | x | x86[_64]/arm64 | x | x | x | |
+## More information about features
+
A. Default is not thread-safe coverage counter updates for better performance,
see [instrumentation/README.llvm.md](../instrumentation/README.llvm.md)
-B. On wrapping coverage counters (255 + 1) skip the 0 value and jump to 1
- instead. This has shown to give better coverage data and is the default;
- see [instrumentation/README.llvm.md](../instrumentation/README.llvm.md)
+
+B. On wrapping coverage counters (255 + 1), skip the 0 value and jump to 1
+ instead. This has shown to give better coverage data and is the default; see
+ [instrumentation/README.llvm.md](../instrumentation/README.llvm.md).
+
C. Instead of forking, reiterate the fuzz target function in a loop (like
- `LLVMFuzzerTestOneInput`. Great speed increase but only work with target
- functions that does not keep state, leak memory or exit;
- see [instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md)
-D. Split any non-8-bit comparison to 8 bit comparison;
- see [instrumentation/README.laf-intel.md](../instrumentation/README.laf-intel.md)
-E. CmpLog is our enhanced [Redqueen](https://www.ndss-symposium.org/ndss-paper/redqueen-fuzzing-with-input-to-state-correspondence/)
- implementation, see see [instrumentation/README.cmplog.md](../instrumentation/README.cmplog.md)
+ `LLVMFuzzerTestOneInput`. Great speed increase but only works with target
+ functions that do not keep state, leak memory, or exit; see
+ [instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md)
+
+D. Split any non-8-bit comparison to 8-bit comparison; see
+ [instrumentation/README.laf-intel.md](../instrumentation/README.laf-intel.md)
+
+E. CmpLog is our enhanced
+ [Redqueen](https://www.ndss-symposium.org/ndss-paper/redqueen-fuzzing-with-input-to-state-correspondence/)
+ implementation, see
+ [instrumentation/README.cmplog.md](../instrumentation/README.cmplog.md)
+
F. Similar and compatible to clang 13+ sancov sanitize-coverage-allow/deny but
for all llvm versions and all our compile modes, only instrument what should
- be instrumented, for more speed, directed fuzzing and less instability;
- see [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md)
+ be instrumented, for more speed, directed fuzzing and less instability; see
+ [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md)
+
G. Vanilla AFL uses coverage where edges could collide to the same coverage
bytes the larger the target is. Our default instrumentation in LTO and
afl-clang-fast (PCGUARD) uses non-colliding coverage that also makes it
- faster. Vanilla AFL style is available with `AFL_LLVM_INSTRUMENT=AFL`;
- see [instrumentation/README.llvm.md](../instrumentation/README.llvm.md)
+ faster. Vanilla AFL style is available with `AFL_LLVM_INSTRUMENT=AFL`; see
+ [instrumentation/README.llvm.md](../instrumentation/README.llvm.md).
+
H.+I. Alternative coverage based on previous edges (NGRAM) or depending on the
caller (CTX), based on
[https://www.usenix.org/system/files/raid2019-wang-jinghan.pdf](https://www.usenix.org/system/files/raid2019-wang-jinghan.pdf);
- see [instrumentation/README.llvm.md](../instrumentation/README.llvm.md)
+ see [instrumentation/README.llvm.md](../instrumentation/README.llvm.md).
+
J. An LTO feature that creates a fuzzing dictionary based on comparisons found
- during compilation/instrumentation. Automatic feature :)
- See [instrumentation/README.lto.md](../instrumentation/README.lto.md)
+ during compilation/instrumentation. Automatic feature :) See
+ [instrumentation/README.lto.md](../instrumentation/README.lto.md)
+
K. The snapshot feature requires a kernel module that was a lot of work to get
right and maintained so it is no longer supported. We have
[nyx_mode](../nyx_mode/README.md) instead.
+
L. Faster fuzzing and less kernel syscall overhead by in-memory fuzz testcase
delivery, see
[instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md)
-1. default for LLVM >= 9.0, environment variable for older version due an
+## More information about instrumentation
+
+1. Default for LLVM >= 9.0, environment variable for older version due an
efficiency bug in previous llvm versions
2. GCC creates non-performant code, hence it is disabled in gcc_plugin
-3. with `AFL_LLVM_THREADSAFE_INST`, disables NeverZero
-4. with pcguard mode and LTO mode for LLVM 11 and newer
-5. upcoming, development in the branch
-6. not compatible with LTO instrumentation and needs at least LLVM v4.1
-7. automatic in LTO mode with LLVM 11 and newer, an extra pass for all LLVM
+3. With `AFL_LLVM_THREADSAFE_INST`, disables NeverZero
+4. With pcguard mode and LTO mode for LLVM 11 and newer
+5. Upcoming, development in the branch
+6. Not compatible with LTO instrumentation and needs at least LLVM v4.1
+7. Automatic in LTO mode with LLVM 11 and newer, an extra pass for all LLVM
versions that write to a file to use with afl-fuzz' `-x`
-8. the snapshot LKM is currently unmaintained due to too many kernel changes
+8. The snapshot LKM is currently unmaintained due to too many kernel changes
coming too fast :-(
9. FRIDA mode is supported on Linux and MacOS for Intel and ARM
10. QEMU/Unicorn is only supported on Linux
@@ -72,6 +90,8 @@ L. Faster fuzzing and less kernel syscall overhead by in-memory fuzz testcase
extension
12. Nyx mode is only supported on Linux and currently restricted to x86_x64
+## Integrated features and patches
+
Among others, the following features and patches have been integrated:
* NeverZero patch for afl-gcc, instrumentation, QEMU mode and unicorn_mode which

Fix structure and formatting