2025-01-17 18:27:46 +03:00

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# Fuzzing
Fuzz testing is an automated software testing method that injects invalid,
malformed, or unexpected inputs to reveal defects and vulnerabilities. A fuzzing
tool monitors the system for exceptions like crashes, information leakage, or
errors, helping developers identify and fix bugs and security loopholes.
## Current state of fuzzing in liboqs
- [ ] kem
- [ ] bike
- [ ] classic_mceliece
- [ ] frodokem
- [ ] hqc
- [ ] kyber
- [ ] ml_kem
- [ ] ntruprime
- [ ] sig
- [x] dilithium
- [x] falcon
- [x] mayo
- [x] ml_dsa
- [x] sphincs
- [ ] sig_stfl
- [ ] lms
- [ ] sig_stfl
- [ ] xmss
## Building and running fuzz tests
Building fuzz tests is very similar to building normally with some optional
steps to target different types of bugs. The most basic ways to build the
fuzz tests is as follows;
```bash
mkdir build && cd build
cmake -GNinja .. -DOQS_BUILD_FUZZ_TESTS=ON
ninja -j$(nproc)
```
You'll now be able to run a fuzz test e.g.
```bash
./tests/fuzz_test_dilithium2
#9764 NEW cov: 4 ft: 708 corp: 100/318b lim: 43 exec/s: 9764 rss: 362Mb L: 41/41 MS: 4 EraseBytes-InsertRepeatedBytes-CMP-ChangeBit- DE: "\0004m\372"-
...
```
The fuzzer will run indefinetely or;
- until it finds a bug and crashes,
- you manually stop the fuzzer i.e. CTRL-C
- you set a timeout using the command line.
For more details on the available command line args please consult the [libfuzzer docs](https://llvm.org/docs/LibFuzzer.html).
## Sanitizers
It is a common pattern to combine fuzzing with various sanitizers to catch different bugs.
One of the simpler sanitizers is the fuzzing sanitizer, which will instrument the code
for coverage driven fuzzing. To enable this simply add this to your environment variables
before configuring cmake;
```
export CFLAGS=-fsanitize=fuzzer-no-link
```
It is common to combine the fuzzer sanitizer with either the [address](https://clang.llvm.org/docs/AddressSanitizer.html)
or the [undefined behaviour sanitizer](https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html). To
add these simply add the relevant flags to BOTH the CFLAGS and LDFLAGS e.g.
```
export CFLAGS=-fsanitize=fuzzer-no-link,address
export LDFLAGS=-fsanitize=address
```
Then rerun cmake as normal i.e.
```bash
mkdir build && cd build
cmake -GNinja .. -DOQS_BUILD_FUZZ_TESTS=ON
ninja -j$(nproc)
```