PersistentFuzzing.md

Persistent fuzzing

Honggfuzz is capable of fuzzing APIs, which is to say; to test new data within the same process. This speeds-up the process of fuzzing APIs greatly

Requirements for hardware-based counter-based fuzzing

• GNU/Linux

HowTo

Prepare a binary in the two following ways:

ASAN-style (LLVMFuzzerTestOneInput)

Two functions must be provided

int LLVMFuzzerTestOneInput(uint8_t *buf, size_t len)

and optionally

int LLVMFuzzerInitialize(int *argc, char ***argv)

Example (test.c):

int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
	TestAPI(buf, len);
	return 0;
}

Compilation

$ hfuzz_cc/hfuzz-clang test.c -o test

Fuzzing

$ honggfuzz -P -- ./test

HF_ITER style

A complete program needs to be prepared, using HF_ITER symbol to fetch new inputs from honggfuzz

Example (test.c):

#include <inttypes.h>

extern HF_ITER(uint8_t** buf, size_t* len);

int main(void) {
	for (;;) {
		size_t len;
		uint8_t *buf;

		HF_ITER(&buf, &len);

		ApiToBeFuzzed(buf, len);
	}
}

Compilation

$ hfuzz_cc/hfuzz-clang test.c -o test

Fuzzing

$ honggfuzz -P -- ./test