Merge "Replay recorded fds and binders in fuzzers" into main

11 files changed, 377 insertions, 69 deletions

diff --git a/libs/binder/RecordedTransaction.cpp b/libs/binder/RecordedTransaction.cpp
index 525ba2e9b9..de2a69f7cf 100644
--- a/libs/binder/RecordedTransaction.cpp
+++ b/libs/binder/RecordedTransaction.cpp
@@ -114,8 +114,8 @@ static_assert(PADDING8(8) == 0);
 
 RecordedTransaction::RecordedTransaction(RecordedTransaction&& t) noexcept {
     mData = t.mData;
-    mSent.setData(t.getDataParcel().data(), t.getDataParcel().dataSize());
-    mReply.setData(t.getReplyParcel().data(), t.getReplyParcel().dataSize());
+    mSentDataOnly.setData(t.getDataParcel().data(), t.getDataParcel().dataSize());
+    mReplyDataOnly.setData(t.getReplyParcel().data(), t.getReplyParcel().dataSize());
 }
 
 std::optional<RecordedTransaction> RecordedTransaction::fromDetails(
@@ -136,12 +136,21 @@ std::optional<RecordedTransaction> RecordedTransaction::fromDetails(
         return std::nullopt;
     }
 
-    if (t.mSent.setData(dataParcel.data(), dataParcel.dataBufferSize()) != android::NO_ERROR) {
+    if (const auto* kernelFields = dataParcel.maybeKernelFields()) {
+        for (size_t i = 0; i < kernelFields->mObjectsSize; i++) {
+            uint64_t offset = kernelFields->mObjects[i];
+            t.mData.mSentObjectData.push_back(offset);
+        }
+    }
+
+    if (t.mSentDataOnly.setData(dataParcel.data(), dataParcel.dataBufferSize()) !=
+        android::NO_ERROR) {
         ALOGE("Failed to set sent parcel data.");
         return std::nullopt;
     }
 
-    if (t.mReply.setData(replyParcel.data(), replyParcel.dataBufferSize()) != android::NO_ERROR) {
+    if (t.mReplyDataOnly.setData(replyParcel.data(), replyParcel.dataBufferSize()) !=
+        android::NO_ERROR) {
         ALOGE("Failed to set reply parcel data.");
         return std::nullopt;
     }
@@ -154,6 +163,7 @@ enum {
     DATA_PARCEL_CHUNK = 2,
     REPLY_PARCEL_CHUNK = 3,
     INTERFACE_NAME_CHUNK = 4,
+    DATA_PARCEL_OBJECT_CHUNK = 5,
     END_CHUNK = 0x00ffffff,
 };
 
@@ -265,21 +275,30 @@ std::optional<RecordedTransaction> RecordedTransaction::fromFile(const unique_fd
                 break;
             }
             case DATA_PARCEL_CHUNK: {
-                if (t.mSent.setData(reinterpret_cast<const unsigned char*>(payloadMap),
-                                    chunk.dataSize) != android::NO_ERROR) {
+                if (t.mSentDataOnly.setData(reinterpret_cast<const unsigned char*>(payloadMap),
+                                            chunk.dataSize) != android::NO_ERROR) {
                     ALOGE("Failed to set sent parcel data.");
                     return std::nullopt;
                 }
                 break;
             }
             case REPLY_PARCEL_CHUNK: {
-                if (t.mReply.setData(reinterpret_cast<const unsigned char*>(payloadMap),
-                                     chunk.dataSize) != android::NO_ERROR) {
+                if (t.mReplyDataOnly.setData(reinterpret_cast<const unsigned char*>(payloadMap),
+                                             chunk.dataSize) != android::NO_ERROR) {
                     ALOGE("Failed to set reply parcel data.");
                     return std::nullopt;
                 }
                 break;
             }
+            case DATA_PARCEL_OBJECT_CHUNK: {
+                const uint64_t* objects = reinterpret_cast<const uint64_t*>(payloadMap);
+                size_t metaDataSize = (chunk.dataSize / sizeof(uint64_t));
+                ALOGI("Total objects found in saved parcel %zu", metaDataSize);
+                for (size_t index = 0; index < metaDataSize; ++index) {
+                    t.mData.mSentObjectData.push_back(objects[index]);
+                }
+                break;
+            }
             case END_CHUNK:
                 break;
             default:
@@ -343,14 +362,26 @@ android::status_t RecordedTransaction::dumpToFile(const unique_fd& fd) const {
         return UNKNOWN_ERROR;
     }
 
-    if (NO_ERROR != writeChunk(fd, DATA_PARCEL_CHUNK, mSent.dataBufferSize(), mSent.data())) {
+    if (NO_ERROR !=
+        writeChunk(fd, DATA_PARCEL_CHUNK, mSentDataOnly.dataBufferSize(), mSentDataOnly.data())) {
         ALOGE("Failed to write sent Parcel to fd %d", fd.get());
         return UNKNOWN_ERROR;
     }
-    if (NO_ERROR != writeChunk(fd, REPLY_PARCEL_CHUNK, mReply.dataBufferSize(), mReply.data())) {
+
+    if (NO_ERROR !=
+        writeChunk(fd, REPLY_PARCEL_CHUNK, mReplyDataOnly.dataBufferSize(),
+                   mReplyDataOnly.data())) {
         ALOGE("Failed to write reply Parcel to fd %d", fd.get());
         return UNKNOWN_ERROR;
     }
+
+    if (NO_ERROR !=
+        writeChunk(fd, DATA_PARCEL_OBJECT_CHUNK, mData.mSentObjectData.size() * sizeof(uint64_t),
+                   reinterpret_cast<const uint8_t*>(mData.mSentObjectData.data()))) {
+        ALOGE("Failed to write sent parcel object metadata to fd %d", fd.get());
+        return UNKNOWN_ERROR;
+    }
+
     if (NO_ERROR != writeChunk(fd, END_CHUNK, 0, NULL)) {
         ALOGE("Failed to write end chunk to fd %d", fd.get());
         return UNKNOWN_ERROR;
@@ -384,10 +415,14 @@ uint32_t RecordedTransaction::getVersion() const {
     return mData.mHeader.version;
 }
 
+const std::vector<uint64_t>& RecordedTransaction::getObjectOffsets() const {
+    return mData.mSentObjectData;
+}
+
 const Parcel& RecordedTransaction::getDataParcel() const {
-    return mSent;
+    return mSentDataOnly;
 }
 
 const Parcel& RecordedTransaction::getReplyParcel() const {
-    return mReply;
+    return mReplyDataOnly;
 }
diff --git a/libs/binder/include/binder/Parcel.h b/libs/binder/include/binder/Parcel.h
index 09da6e3c4a..d7096d8a75 100644
--- a/libs/binder/include/binder/Parcel.h
+++ b/libs/binder/include/binder/Parcel.h
@@ -55,6 +55,9 @@ class String8;
 class TextOutput;
 namespace binder {
 class Status;
+namespace debug {
+class RecordedTransaction;
+}
 }
 
 class Parcel {
@@ -1443,6 +1446,9 @@ private:
     // TODO(b/202029388): Remove 'getBlobAshmemSize' once no prebuilts reference
     // this
     size_t getBlobAshmemSize() const;
+
+    // Needed so that we can save object metadata to the disk
+    friend class android::binder::debug::RecordedTransaction;
 };
 
 // ---------------------------------------------------------------------------
diff --git a/libs/binder/include/binder/RecordedTransaction.h b/libs/binder/include/binder/RecordedTransaction.h
index 505c1992b9..f0bee7f39e 100644
--- a/libs/binder/include/binder/RecordedTransaction.h
+++ b/libs/binder/include/binder/RecordedTransaction.h
@@ -50,6 +50,7 @@ public:
     uint32_t getVersion() const;
     const Parcel& getDataParcel() const;
     const Parcel& getReplyParcel() const;
+    const std::vector<uint64_t>& getObjectOffsets() const;
 
 private:
     RecordedTransaction() = default;
@@ -75,10 +76,11 @@ private:
     struct MovableData { // movable
         TransactionHeader mHeader;
         std::string mInterfaceName;
+        std::vector<uint64_t> mSentObjectData; /* Object Offsets */
     };
     MovableData mData;
-    Parcel mSent;
-    Parcel mReply;
+    Parcel mSentDataOnly;
+    Parcel mReplyDataOnly;
 };
 
 } // namespace binder::debug
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index dd2be94a76..aba2319485 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -69,10 +69,14 @@ cc_test {
 cc_test {
     name: "binderRecordReplayTest",
     srcs: ["binderRecordReplayTest.cpp"],
+    cflags: [
+        "-DBINDER_WITH_KERNEL_IPC",
+    ],
     shared_libs: [
         "libbinder",
         "libcutils",
         "libutils",
+        "liblog",
     ],
     static_libs: [
         "binderRecordReplayTestIface-cpp",
@@ -96,6 +100,9 @@ aidl_interface {
             enabled: true,
             platform_apis: true,
         },
+        ndk: {
+            enabled: false,
+        },
     },
 }
 
diff --git a/libs/binder/tests/IBinderRecordReplayTest.aidl b/libs/binder/tests/IBinderRecordReplayTest.aidl
index bd6b03c6e0..29267e91c6 100644
--- a/libs/binder/tests/IBinderRecordReplayTest.aidl
+++ b/libs/binder/tests/IBinderRecordReplayTest.aidl
@@ -69,4 +69,10 @@ interface IBinderRecordReplayTest {
 
     void setSingleDataParcelableArray(in SingleDataParcelable[] input);
     SingleDataParcelable[] getSingleDataParcelableArray();
+
+    void setBinder(in IBinder binder);
+    IBinder getBinder();
+
+    void setFileDescriptor(in FileDescriptor fd);
+    FileDescriptor getFileDescriptor();
 }
diff --git a/libs/binder/tests/binderRecordReplayTest.cpp b/libs/binder/tests/binderRecordReplayTest.cpp
index 73c0a94ce2..b975fad2c9 100644
--- a/libs/binder/tests/binderRecordReplayTest.cpp
+++ b/libs/binder/tests/binderRecordReplayTest.cpp
@@ -24,7 +24,10 @@
 #include <binder/RecordedTransaction.h>
 #include <binder/unique_fd.h>
 
+#include <cutils/ashmem.h>
+
 #include <fuzzbinder/libbinder_driver.h>
+#include <fuzzbinder/random_binder.h>
 #include <fuzzer/FuzzedDataProvider.h>
 #include <fuzzseeds/random_parcel_seeds.h>
 
@@ -37,6 +40,7 @@
 
 using namespace android;
 using android::generateSeedsFromRecording;
+using android::RandomBinder;
 using android::binder::borrowed_fd;
 using android::binder::Status;
 using android::binder::unique_fd;
@@ -44,6 +48,7 @@ using android::binder::debug::RecordedTransaction;
 using parcelables::SingleDataParcelable;
 
 const String16 kServerName = String16("binderRecordReplay");
+extern std::string kRandomInterfaceName;
 
 #define GENERATE_GETTER_SETTER_PRIMITIVE(name, T) \
     Status set##name(T input) {                   \
@@ -81,6 +86,7 @@ public:
 
     GENERATE_GETTER_SETTER(String, String16);
     GENERATE_GETTER_SETTER(SingleDataParcelable, SingleDataParcelable);
+    GENERATE_GETTER_SETTER(Binder, sp<IBinder>);
 
     GENERATE_GETTER_SETTER(BooleanArray, std::vector<bool>);
     GENERATE_GETTER_SETTER(ByteArray, std::vector<uint8_t>);
@@ -91,12 +97,22 @@ public:
     GENERATE_GETTER_SETTER(DoubleArray, std::vector<double>);
     GENERATE_GETTER_SETTER(StringArray, std::vector<::android::String16>);
     GENERATE_GETTER_SETTER(SingleDataParcelableArray, std::vector<SingleDataParcelable>);
+
+    Status setFileDescriptor(unique_fd input) {
+        mFd = std::move(unique_fd(dup(input)));
+        return Status::ok();
+    }
+
+    Status getFileDescriptor(unique_fd* output) {
+        *output = std::move(unique_fd(dup(mFd)));
+        return Status::ok();
+    }
+    unique_fd mFd;
 };
 
 std::vector<uint8_t> retrieveData(borrowed_fd fd) {
     struct stat fdStat;
     EXPECT_TRUE(fstat(fd.get(), &fdStat) != -1);
-    EXPECT_TRUE(fdStat.st_size != 0);
 
     std::vector<uint8_t> buffer(fdStat.st_size);
     auto readResult = android::base::ReadFully(fd, buffer.data(), fdStat.st_size);
@@ -115,6 +131,7 @@ void replayFuzzService(const sp<BpBinder>& binder, const RecordedTransaction& tr
     // Read the data which has been written to seed corpus
     ASSERT_EQ(0, lseek(seedFd.get(), 0, SEEK_SET));
     std::vector<uint8_t> seedData = retrieveData(seedFd);
+    EXPECT_TRUE(seedData.size() != 0);
 
     // use fuzzService to replay the corpus
     FuzzedDataProvider provider(seedData.data(), seedData.size());
@@ -148,7 +165,14 @@ public:
     template <typename T, typename U>
     void recordReplay(Status (IBinderRecordReplayTest::*set)(T), U recordedValue,
                       Status (IBinderRecordReplayTest::*get)(U*), U changedValue) {
-        auto replayFunctions = {&replayBinder, &replayFuzzService};
+        using ReplayFunc = decltype(&replayFuzzService);
+        vector<ReplayFunc> replayFunctions = {&replayFuzzService};
+        if (!std::is_same_v<U, unique_fd> && !std::is_same_v<U, sp<IBinder>>) {
+            // Parcel retrieved from record replay doesn't have object information. use it for
+            // replaying primitive types only.
+            replayFunctions.push_back(&replayBinder);
+        }
+
         for (auto replayFunc : replayFunctions) {
             unique_fd fd(open("/data/local/tmp/binderRecordReplayTest.rec",
                               O_RDWR | O_CREAT | O_CLOEXEC, 0666));
@@ -156,7 +180,7 @@ public:
 
             // record a transaction
             mBpBinder->startRecordingBinder(fd);
-            auto status = (*mInterface.*set)(recordedValue);
+            auto status = (*mInterface.*set)(std::move(recordedValue));
             EXPECT_TRUE(status.isOk());
             mBpBinder->stopRecordingBinder();
 
@@ -164,16 +188,22 @@ public:
             U output;
             status = (*mInterface.*get)(&output);
             EXPECT_TRUE(status.isOk());
-            EXPECT_EQ(output, recordedValue);
+
+            // Expect this equal only if types are primitives
+            if (!std::is_same_v<U, unique_fd> && !std::is_same_v<U, sp<IBinder>>) {
+                EXPECT_EQ(output, recordedValue);
+            }
 
             // write over the existing state
-            status = (*mInterface.*set)(changedValue);
+            status = (*mInterface.*set)(std::move(changedValue));
             EXPECT_TRUE(status.isOk());
 
             status = (*mInterface.*get)(&output);
             EXPECT_TRUE(status.isOk());
 
-            EXPECT_EQ(output, changedValue);
+            if (!std::is_same_v<U, unique_fd> && !std::is_same_v<U, sp<IBinder>>) {
+                EXPECT_EQ(output, changedValue);
+            }
 
             // replay transaction
             ASSERT_EQ(0, lseek(fd.get(), 0, SEEK_SET));
@@ -186,7 +216,23 @@ public:
 
             status = (*mInterface.*get)(&output);
             EXPECT_TRUE(status.isOk());
-            EXPECT_EQ(output, recordedValue);
+
+            // FDs and binders will be replaced with random fd and random binders
+            if constexpr (std::is_same_v<U, unique_fd>) {
+                // verify that replayed fd is /dev/null. This is being replayed from random_fd.cpp
+                // and choosing /dav/null while generating seed in binder2corpus
+                std::string fdPath = "/proc/self/fd/" + std::to_string(output.get());
+                char path[PATH_MAX];
+                ASSERT_GT(readlink(fdPath.c_str(), path, sizeof(path)), 0);
+                EXPECT_EQ(strcmp("/dev/null", path), 0);
+            } else if constexpr (std::is_same_v<U, sp<IBinder>>) {
+                // This is binder is replayed from random_binder.cpp using seed data which writes
+                // this interface.
+                EXPECT_EQ(String16(kRandomInterfaceName.c_str(), kRandomInterfaceName.size()),
+                          output->getInterfaceDescriptor());
+            } else {
+                ASSERT_EQ(recordedValue, output);
+            }
         }
     }
 
@@ -319,6 +365,32 @@ TEST_F(BinderRecordReplayTest, ReplaySingleDataParcelableArray) {
                  &IBinderRecordReplayTest::getSingleDataParcelableArray, changed);
 }
 
+TEST_F(BinderRecordReplayTest, ReplayBinder) {
+    vector<uint8_t> data = {0x8A, 0x19, 0x0D, 0x44, 0x37, 0x0D, 0x38, 0x5E, 0x9B, 0xAA, 0xF3, 0xDA};
+    sp<IBinder> saved = new RandomBinder(String16("random_interface"), std::move(data));
+    sp<IBinder> changed = IInterface::asBinder(defaultServiceManager());
+    recordReplay(&IBinderRecordReplayTest::setBinder, saved, &IBinderRecordReplayTest::getBinder,
+                 changed);
+}
+
+TEST_F(BinderRecordReplayTest, ReplayFd) {
+    // Write something to both fds we are setting
+    unique_fd saved(open("/data/local/tmp/test_fd", O_RDWR | O_CREAT | O_CLOEXEC, 0666));
+    std::string contentSaved = "This will be never read again for recorded fd!";
+    CHECK(android::base::WriteFully(saved, contentSaved.data(), contentSaved.size()))
+            << saved.get();
+
+    unique_fd changed(open("/data/local/tmp/test_des", O_RDWR | O_CREAT | O_CLOEXEC, 0666));
+    std::string contentChanged = "This will be never read again from changed fd!";
+    CHECK(android::base::WriteFully(changed, contentChanged.data(), contentChanged.size()))
+            << changed.get();
+
+    // When fds are replayed, it will be replaced by /dev/null..reading from it should yield
+    // null data
+    recordReplay(&IBinderRecordReplayTest::setFileDescriptor, std::move(unique_fd(dup(saved))),
+                 &IBinderRecordReplayTest::getFileDescriptor, std::move(unique_fd(dup(changed))));
+}
+
 int main(int argc, char** argv) {
     ::testing::InitGoogleTest(&argc, argv);
 
diff --git a/libs/binder/tests/parcel_fuzzer/Android.bp b/libs/binder/tests/parcel_fuzzer/Android.bp
index 83db6c9b6d..fbab8f08a9 100644
--- a/libs/binder/tests/parcel_fuzzer/Android.bp
+++ b/libs/binder/tests/parcel_fuzzer/Android.bp
@@ -131,6 +131,13 @@ cc_library {
         "libcutils",
         "libutils",
     ],
+    static_libs: [
+        "libbinder_random_parcel",
+    ],
+    include_dirs: [
+        "bionic/libc/kernel/android/uapi/",
+        "bionic/libc/kernel/uapi/",
+    ],
     local_include_dirs: [
         "include_random_parcel_seeds",
     ],
@@ -140,8 +147,12 @@ cc_library {
 cc_binary_host {
     name: "binder2corpus",
     static_libs: [
+        "libbinder_random_parcel",
         "libbinder_random_parcel_seeds",
     ],
+    cflags: [
+        "-DBINDER_WITH_KERNEL_IPC",
+    ],
     srcs: [
         "binder2corpus/binder2corpus.cpp",
     ],
@@ -149,5 +160,6 @@ cc_binary_host {
         "libbase",
         "libbinder",
         "libutils",
+        "libcutils",
     ],
 }
diff --git a/libs/binder/tests/parcel_fuzzer/include_random_parcel/fuzzbinder/random_binder.h b/libs/binder/tests/parcel_fuzzer/include_random_parcel/fuzzbinder/random_binder.h
index 8fc9263b98..7a1688b7b7 100644
--- a/libs/binder/tests/parcel_fuzzer/include_random_parcel/fuzzbinder/random_binder.h
+++ b/libs/binder/tests/parcel_fuzzer/include_random_parcel/fuzzbinder/random_binder.h
@@ -16,11 +16,25 @@
 
 #pragma once
 
+#include <binder/Binder.h>
 #include <binder/IBinder.h>
 #include <fuzzer/FuzzedDataProvider.h>
 
 namespace android {
 
+class RandomBinder : public BBinder {
+public:
+    RandomBinder(const String16& descriptor, std::vector<uint8_t>&& bytes);
+    const String16& getInterfaceDescriptor() const override;
+    status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) override;
+
+private:
+    String16 mDescriptor;
+    // note may not all be used
+    std::vector<uint8_t> mBytes;
+    FuzzedDataProvider mProvider;
+};
+
 // Get a random binder object for use in fuzzing.
 //
 // May return nullptr.
diff --git a/libs/binder/tests/parcel_fuzzer/random_binder.cpp b/libs/binder/tests/parcel_fuzzer/random_binder.cpp
index 8a1fecb212..f41c35bfbe 100644
--- a/libs/binder/tests/parcel_fuzzer/random_binder.cpp
+++ b/libs/binder/tests/parcel_fuzzer/random_binder.cpp
@@ -21,56 +21,52 @@
 #include <binder/IInterface.h>
 #include <binder/IServiceManager.h>
 
+size_t kRandomInterfaceLength = 50;
 namespace android {
 
-class RandomBinder : public BBinder {
-public:
-    RandomBinder(const String16& descriptor, std::vector<uint8_t>&& bytes)
-          : mDescriptor(descriptor),
-            mBytes(std::move(bytes)),
-            mProvider(mBytes.data(), mBytes.size()) {}
-    const String16& getInterfaceDescriptor() const override { return mDescriptor; }
+RandomBinder::RandomBinder(const String16& descriptor, std::vector<uint8_t>&& bytes)
+      : mDescriptor(descriptor),
+        mBytes(std::move(bytes)),
+        mProvider(mBytes.data(), mBytes.size()) {}
 
-    status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags) override {
-        (void)code;
-        (void)data;
-        (void)reply;
-        (void)flags; // note - for maximum coverage even ignore if oneway
+const String16& RandomBinder::getInterfaceDescriptor() const {
+    return mDescriptor;
+}
 
-        if (mProvider.ConsumeBool()) {
-            return mProvider.ConsumeIntegral<status_t>();
-        }
+status_t RandomBinder::onTransact(uint32_t code, const Parcel& data, Parcel* reply,
+                                  uint32_t flags) {
+    (void)code;
+    (void)data;
+    (void)reply;
+    (void)flags; // note - for maximum coverage even ignore if oneway
 
-        if (reply == nullptr) return OK;
+    if (mProvider.ConsumeBool()) {
+        return mProvider.ConsumeIntegral<status_t>();
+    }
 
-        // TODO: things we could do to increase state space
-        // - also pull FDs and binders from 'data'
-        //     (optionally combine these into random parcel 'options')
-        // - also pull FDs and binders from random parcel 'options'
-        RandomParcelOptions options;
+    if (reply == nullptr) return OK;
 
-        // random output
-        std::vector<uint8_t> subData = mProvider.ConsumeBytes<uint8_t>(
-                mProvider.ConsumeIntegralInRange<size_t>(0, mProvider.remaining_bytes()));
-        fillRandomParcel(reply, FuzzedDataProvider(subData.data(), subData.size()), &options);
+    // TODO: things we could do to increase state space
+    // - also pull FDs and binders from 'data'
+    //     (optionally combine these into random parcel 'options')
+    // - also pull FDs and binders from random parcel 'options'
+    RandomParcelOptions options;
 
-        return OK;
-    }
+    // random output
+    std::vector<uint8_t> subData = mProvider.ConsumeBytes<uint8_t>(
+            mProvider.ConsumeIntegralInRange<size_t>(0, mProvider.remaining_bytes()));
+    fillRandomParcel(reply, FuzzedDataProvider(subData.data(), subData.size()), &options);
 
-private:
-    String16 mDescriptor;
-
-    // note may not all be used
-    std::vector<uint8_t> mBytes;
-    FuzzedDataProvider mProvider;
-};
+    return OK;
+}
 
 sp<IBinder> getRandomBinder(FuzzedDataProvider* provider) {
     auto makeFunc = provider->PickValueInArray<const std::function<sp<IBinder>()>>({
             [&]() {
                 // descriptor is the length of a class name, e.g.
                 // "some.package.Foo"
-                std::string str = provider->ConsumeRandomLengthString(100 /*max length*/);
+                std::string str =
+                        provider->ConsumeRandomLengthString(kRandomInterfaceLength /*max length*/);
 
                 // arbitrarily consume remaining data to create a binder that can return
                 // random results - coverage guided fuzzer should ensure all of the remaining
diff --git a/libs/binder/tests/parcel_fuzzer/random_parcel.cpp b/libs/binder/tests/parcel_fuzzer/random_parcel.cpp
index 4e58dc4899..62b84330cd 100644
--- a/libs/binder/tests/parcel_fuzzer/random_parcel.cpp
+++ b/libs/binder/tests/parcel_fuzzer/random_parcel.cpp
@@ -73,7 +73,7 @@ void fillRandomParcel(Parcel* p, FuzzedDataProvider&& provider, RandomParcelOpti
                         return;
                     }
 
-                    if (options->extraFds.size() > 0 && provider.ConsumeBool()) {
+                    if (provider.ConsumeBool() && options->extraFds.size() > 0) {
                         const unique_fd& fd = options->extraFds.at(
                                 provider.ConsumeIntegralInRange<size_t>(0,
                                                                         options->extraFds.size() -
@@ -102,7 +102,7 @@ void fillRandomParcel(Parcel* p, FuzzedDataProvider&& provider, RandomParcelOpti
                     }
 
                     sp<IBinder> binder;
-                    if (options->extraBinders.size() > 0 && provider.ConsumeBool()) {
+                    if (provider.ConsumeBool() && options->extraBinders.size() > 0) {
                         binder = options->extraBinders.at(
                                 provider.ConsumeIntegralInRange<size_t>(0,
                                                                         options->extraBinders
diff --git a/libs/binder/tests/parcel_fuzzer/random_parcel_seeds.cpp b/libs/binder/tests/parcel_fuzzer/random_parcel_seeds.cpp
index 7b3c80642b..fd9777a916 100644
--- a/libs/binder/tests/parcel_fuzzer/random_parcel_seeds.cpp
+++ b/libs/binder/tests/parcel_fuzzer/random_parcel_seeds.cpp
@@ -14,16 +14,26 @@
  * limitations under the License.
  */
 
+#include <linux/android/binder.h>
+
 #include <android-base/logging.h>
 
+#include <binder/Parcel.h>
 #include <binder/RecordedTransaction.h>
 
 #include <fuzzseeds/random_parcel_seeds.h>
 
+#include <stack>
+#include <string>
 #include "../../file.h"
 
 using android::binder::borrowed_fd;
 using android::binder::WriteFully;
+using std::stack;
+
+extern size_t kRandomInterfaceLength;
+// Keep this in sync with max_length in random_binder.cpp while creating a RandomBinder
+std::string kRandomInterfaceName(kRandomInterfaceLength, 'i');
 
 namespace android {
 namespace impl {
@@ -66,6 +76,162 @@ void writeReversedBuffer(std::vector<uint8_t>& integralBuffer, T val) {
 
 } // namespace impl
 
+struct ProviderMetadata {
+    size_t position;
+    size_t value;
+
+    ProviderMetadata() {
+        value = 0;
+        position = 0;
+    }
+};
+
+// Assuming current seed path is inside the fillRandomParcel function, start of the loop.
+void writeRandomBinder(borrowed_fd fd, vector<uint8_t>& fillParcelBuffer,
+                       stack<ProviderMetadata>& remainingPositions) {
+    // Choose 2 index in array
+    size_t fillFuncIndex = 2;
+    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(2),
+                              fillFuncIndex);
+
+    // navigate to getRandomBinder. provide consume bool false
+    bool flag = false;
+    impl::writeReversedBuffer(fillParcelBuffer, flag);
+
+    // selecting RandomBinder, other binders in the list are not recorded as KernelObjects
+    size_t randomBinderIndex = 0;
+    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(2),
+                              randomBinderIndex);
+
+    // write random string of length 100 in actual buffer array.
+    CHECK(WriteFully(fd, kRandomInterfaceName.c_str(), kRandomInterfaceName.size())) << fd.get();
+
+    // These will be bytes which are used inside of RandomBinder
+    // simplest path for these bytes is going to be consume bool -> return random status
+    vector<uint8_t> randomBinderBuffer;
+
+    bool returnRandomInt = true;
+    impl::writeReversedBuffer(randomBinderBuffer, returnRandomInt);
+
+    status_t randomStatus = 0;
+    impl::writeReversedBuffer(randomBinderBuffer, randomStatus);
+
+    // write integral in range to consume bytes for random binder
+    ProviderMetadata providerData;
+    providerData.position = fillParcelBuffer.size();
+    providerData.value = randomBinderBuffer.size();
+    remainingPositions.push(providerData);
+
+    // Write to fd
+    CHECK(WriteFully(fd, randomBinderBuffer.data(), randomBinderBuffer.size())) << fd.get();
+}
+
+// Assuming current seed path is inside the fillRandomParcelFunction, start of the loop.
+void writeRandomFd(vector<uint8_t>& fillParcelBuffer) {
+    // path to random fd
+    size_t fillFuncIndex = 1;
+    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(2),
+                              fillFuncIndex);
+
+    bool flag = false;
+    impl::writeReversedBuffer(fillParcelBuffer, flag);
+
+    // go for /dev/null index 1
+    size_t fdIndex = 1;
+    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(3),
+                              fdIndex);
+}
+
+void writeParcelData(borrowed_fd fd, vector<uint8_t>& fillParcelBuffer,
+                     stack<ProviderMetadata>& remainingPositions, const uint8_t* data, size_t start,
+                     size_t length) {
+    // need to write parcel data till next offset with instructions to pick random bytes till offset
+    size_t fillFuncIndex = 0;
+    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(2),
+                              fillFuncIndex);
+
+    // provide how much bytes to read in control buffer
+    ProviderMetadata providerData;
+    providerData.position = fillParcelBuffer.size();
+    providerData.value = length;
+    remainingPositions.push(providerData);
+
+    // provide actual bytes
+    CHECK(WriteFully(fd, data + start, length)) << fd.get();
+}
+
+/**
+ *   Generate sequence of copy data, write fd and write binder instructions and required data.
+ *   Data which will be read using consumeBytes is written to fd directly. Data which is read in
+ *   form integer is consumed from rear end FuzzedDataProvider. So insert it in fillParcelBuffer and
+ *   then write to fd
+ */
+size_t regenerateParcel(borrowed_fd fd, vector<uint8_t>& fillParcelBuffer, const Parcel& p,
+                        size_t dataSize, const vector<uint64_t>& objectOffsets) {
+    stack<ProviderMetadata> remainingPositions;
+    size_t copiedDataPosition = 0;
+    const uint8_t* parcelData = p.data();
+    size_t numBinders = 0;
+    size_t numFds = 0;
+
+    for (auto offset : objectOffsets) {
+        // Check what type of object is present here
+        const flat_binder_object* flatObject =
+                reinterpret_cast<const flat_binder_object*>(parcelData + offset);
+        // Copy till the object offset
+        writeParcelData(fd, fillParcelBuffer, remainingPositions, parcelData, copiedDataPosition,
+                        offset - copiedDataPosition);
+        copiedDataPosition = offset;
+        if (flatObject->hdr.type == BINDER_TYPE_BINDER ||
+            flatObject->hdr.type == BINDER_TYPE_HANDLE) {
+            writeRandomBinder(fd, fillParcelBuffer, remainingPositions);
+            numBinders++;
+            // In case of binder, stability is written after the binder object.
+            // We want to move the copiedDataPosition further to account for this stability field
+            copiedDataPosition += sizeof(int32_t) + sizeof(flat_binder_object);
+        } else if (flatObject->hdr.type == BINDER_TYPE_FD) {
+            writeRandomFd(fillParcelBuffer);
+            numFds++;
+            copiedDataPosition += sizeof(flat_binder_object);
+        }
+    }
+
+    if (copiedDataPosition < dataSize) {
+        // copy remaining data from recorded parcel -> last Object to end of the data
+        writeParcelData(fd, fillParcelBuffer, remainingPositions, parcelData, copiedDataPosition,
+                        dataSize - copiedDataPosition);
+    }
+
+    // We need to write bytes for selecting integer within range of  0 to provide.remaining_bytes()
+    // is called.
+    size_t totalWrittenBytes = dataSize - (sizeof(flat_binder_object) * objectOffsets.size()) -
+            (sizeof(int32_t) * numBinders) +
+            (kRandomInterfaceName.size() /*Interface String*/ + sizeof(bool) + sizeof(status_t)) *
+                    numBinders;
+
+    // Code in fuzzService relies on provider.remaining_bytes() to select random bytes using
+    // consume integer. use the calculated remaining_bytes to generate byte buffer which can
+    // generate required fds and binders in fillRandomParcel function.
+    while (!remainingPositions.empty()) {
+        auto meta = remainingPositions.top();
+        remainingPositions.pop();
+        size_t remainingBytes = totalWrittenBytes + fillParcelBuffer.size() - meta.position;
+
+        vector<uint8_t> remReversedBytes;
+        impl::writeReversedBuffer(remReversedBytes, static_cast<size_t>(0), remainingBytes,
+                                  meta.value);
+        // Check the order of buffer which is being written
+        fillParcelBuffer.insert(fillParcelBuffer.end() - meta.position, remReversedBytes.begin(),
+                                remReversedBytes.end());
+    }
+
+    return totalWrittenBytes;
+}
+
+/**
+ * Current corpus format
+ * |Reserved bytes(8)|parcel data|fillParcelBuffer|integralBuffer|
+ */
 void generateSeedsFromRecording(borrowed_fd fd,
                                 const binder::debug::RecordedTransaction& transaction) {
     // Write Reserved bytes for future use
@@ -123,17 +289,9 @@ void generateSeedsFromRecording(borrowed_fd fd,
     uint8_t writeHeaderInternal = 0;
     impl::writeReversedBuffer(fillParcelBuffer, writeHeaderInternal);
 
-    // Choose to write data in parcel
-    size_t fillFuncIndex = 0;
-    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), static_cast<size_t>(2),
-                              fillFuncIndex);
-
-    // Write parcel data size from recorded transaction
-    size_t toWrite = transaction.getDataParcel().dataBufferSize();
-    impl::writeReversedBuffer(fillParcelBuffer, static_cast<size_t>(0), toWrite, toWrite);
-
-    // Write parcel data with size towrite from recorded transaction
-    CHECK(WriteFully(fd, dataParcel.data(), toWrite)) << fd.get();
+    auto objectMetadata = transaction.getObjectOffsets();
+    size_t toWrite = regenerateParcel(fd, fillParcelBuffer, dataParcel, dataParcel.dataBufferSize(),
+                                      objectMetadata);
 
     // Write Fill Parcel buffer size in integralBuffer so that fuzzService knows size of data
     size_t subDataSize = toWrite + fillParcelBuffer.size();