binder_parcel_fuzzer: use FuzzedDataProvider
This makes the code a little more readable and paves the way for having
more complicated Parcel creation.
As a side effect, this allows the number of instructions to be run on a
parcel to be larger than the size of the parcel itself, so we should
increase meaningful coverage for small parcel sizes.
Bug: N/A
Test: binder_parcel_fuzzer for several minutes
Change-Id: I30a8f6c40e5255b3d01b2bacc52990cfb50150f0
diff --git a/libs/binder/fuzzer/main.cpp b/libs/binder/fuzzer/main.cpp
index 6657edb..db23938 100644
--- a/libs/binder/fuzzer/main.cpp
+++ b/libs/binder/fuzzer/main.cpp
@@ -21,15 +21,25 @@
#include "util.h"
#include <android-base/logging.h>
+#include <fuzzer/FuzzedDataProvider.h>
#include <cstdlib>
#include <ctime>
template <typename P>
-void doFuzz(
- const std::vector<ParcelRead<P>>& reads,
- const std::vector<uint8_t>& input,
- const std::vector<uint8_t>& instructions) {
+void doFuzz(const char* backend, const std::vector<ParcelRead<P>>& reads,
+ FuzzedDataProvider* provider) {
+ // Allow some majority of the bytes to be dedicated to telling us what to
+ // do. The fixed value added here represents that we want to test doing a
+ // lot of 'instructions' even on really short parcels.
+ size_t maxInstructions = 20 + (provider->remaining_bytes() * 2 / 3);
+ // but don't always use that many instructions. We want to allow the fuzzer
+ // to explore large parcels with few instructions if it wants to.
+ std::vector<uint8_t> instructions = provider->ConsumeBytes<uint8_t>(
+ provider->ConsumeIntegralInRange<size_t>(0, maxInstructions));
+
+ // TODO: generate 'objects' data
+ std::vector<uint8_t> input = provider->ConsumeRemainingBytes<uint8_t>();
P p;
p.setData(input.data(), input.size());
@@ -37,7 +47,11 @@
// since we are only using a byte to index
CHECK(reads.size() <= 255) << reads.size();
- for (size_t i = 0; i < instructions.size() - 1; i += 2) {
+ FUZZ_LOG() << "backend: " << backend;
+ FUZZ_LOG() << "input: " << hexString(input);
+ FUZZ_LOG() << "instructions: " << hexString(instructions);
+
+ for (size_t i = 0; i + 1 < instructions.size(); i += 2) {
uint8_t a = instructions[i];
uint8_t readIdx = a % reads.size();
@@ -53,58 +67,28 @@
}
}
-void fuzz(uint8_t options, const std::vector<uint8_t>& input, const std::vector<uint8_t>& instructions) {
- uint8_t parcelType = options & 0x3;
-
- switch (parcelType) {
- case 0x0:
- doFuzz<::android::hardware::Parcel>(HWBINDER_PARCEL_READ_FUNCTIONS, input,
- instructions);
- break;
- case 0x1:
- doFuzz<::android::Parcel>(BINDER_PARCEL_READ_FUNCTIONS, input, instructions);
- break;
- case 0x2:
- doFuzz<NdkParcelAdapter>(BINDER_NDK_PARCEL_READ_FUNCTIONS, input, instructions);
- break;
- case 0x3:
- /*reserved for future use*/
- break;
- default:
- LOG_ALWAYS_FATAL("unknown parcel type %d", static_cast<int>(parcelType));
- }
-}
-
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
if (size <= 1) return 0; // no use
// avoid timeouts, see b/142617274, b/142473153
if (size > 50000) return 0;
- uint8_t options = *data;
- data++;
- size--;
+ FuzzedDataProvider provider = FuzzedDataProvider(data, size);
- // TODO: generate 'objects' data
+ const std::function<void(FuzzedDataProvider*)> fuzzBackend[3] = {
+ [](FuzzedDataProvider* provider) {
+ doFuzz<::android::hardware::Parcel>("hwbinder", HWBINDER_PARCEL_READ_FUNCTIONS,
+ provider);
+ },
+ [](FuzzedDataProvider* provider) {
+ doFuzz<::android::Parcel>("binder", BINDER_PARCEL_READ_FUNCTIONS, provider);
+ },
+ [](FuzzedDataProvider* provider) {
+ doFuzz<NdkParcelAdapter>("binder_ndk", BINDER_NDK_PARCEL_READ_FUNCTIONS, provider);
+ },
+ };
- // data to fill out parcel
- size_t inputLen = size / 2;
- std::vector<uint8_t> input(data, data + inputLen);
- data += inputLen;
- size -= inputLen;
+ provider.PickValueInArray(fuzzBackend)(&provider);
- // data to use to determine what to do
- size_t instructionLen = size;
- std::vector<uint8_t> instructions(data, data + instructionLen);
- data += instructionLen;
- size -= instructionLen;
-
- CHECK(size == 0) << "size: " << size;
-
- FUZZ_LOG() << "options: " << (int)options << " inputLen: " << inputLen << " instructionLen: " << instructionLen;
- FUZZ_LOG() << "input: " << hexString(input);
- FUZZ_LOG() << "instructions: " << hexString(instructions);
-
- fuzz(options, input, instructions);
return 0;
}