8 files changed, 782 insertions, 0 deletions
diff --git a/src/rocksdb/fuzz/.gitignore b/src/rocksdb/fuzz/.gitignore
new file mode 100644
index 000000000..9dab42105
--- /dev/null
+++ b/src/rocksdb/fuzz/.gitignore
@@ -0,0 +1,5 @@
+db_fuzzer
+db_map_fuzzer
+sst_file_writer_fuzzer
+
+proto/gen/*
diff --git a/src/rocksdb/fuzz/Makefile b/src/rocksdb/fuzz/Makefile
new file mode 100644
index 000000000..b83040504
--- /dev/null
+++ b/src/rocksdb/fuzz/Makefile
@@ -0,0 +1,67 @@
+# Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+# This source code is licensed under both the GPLv2 (found in the
+# COPYING file in the root directory) and Apache 2.0 License
+# (found in the LICENSE.Apache file in the root directory).
+
+ROOT_DIR = $(abspath $(shell pwd)/../)
+
+include $(ROOT_DIR)/make_config.mk
+
+PROTOBUF_CFLAGS = `pkg-config --cflags protobuf`
+PROTOBUF_LDFLAGS = `pkg-config --libs protobuf`
+
+PROTOBUF_MUTATOR_CFLAGS = `pkg-config --cflags libprotobuf-mutator`
+PROTOBUF_MUTATOR_LDFLAGS = `pkg-config --libs libprotobuf-mutator`
+
+ROCKSDB_INCLUDE_DIR = $(ROOT_DIR)/include
+ROCKSDB_LIB_DIR = $(ROOT_DIR)
+
+PROTO_IN = $(ROOT_DIR)/fuzz/proto
+PROTO_OUT = $(ROOT_DIR)/fuzz/proto/gen
+
+ifneq ($(FUZZ_ENV), ossfuzz)
+CC = $(CXX)
+CCFLAGS += -Wall -fsanitize=address,fuzzer
+CFLAGS += $(PLATFORM_CXXFLAGS) $(PROTOBUF_CFLAGS) $(PROTOBUF_MUTATOR_CFLAGS) -I$(PROTO_OUT) -I$(ROCKSDB_INCLUDE_DIR) -I$(ROCKSDB_LIB_DIR)
+LDFLAGS += $(PLATFORM_LDFLAGS) $(PROTOBUF_MUTATOR_LDFLAGS) $(PROTOBUF_LDFLAGS) -L$(ROCKSDB_LIB_DIR) -lrocksdb
+else
+# OSS-Fuzz sets various environment flags that are used for compilation.
+# These environment flags depend on which type of sanitizer build is being
+# used, however, an ASan build would set the environment flags as follows:
+# CFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only \
+         -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address \
+         -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link"
+# CXXFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only \
+           -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address \
+           -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link \
+           -stdlib=libc++"
+# LIB_FUZZING_ENGINE="-fsanitize=fuzzer"
+CC = $(CXX)
+CCFLAGS = $(CXXFLAGS)
+CFLAGS += $(PROTOBUF_CFLAGS) $(PROTOBUF_MUTATOR_CFLAGS) -I$(PROTO_OUT) -I$(ROCKSDB_INCLUDE_DIR) -I$(ROCKSDB_LIB_DIR)
+LDFLAGS += $(PLATFORM_LDFLAGS) $(LIB_FUZZING_ENGINE) $(PROTOBUF_MUTATOR_LDFLAGS) $(PROTOBUF_LDFLAGS) -L$(ROCKSDB_LIB_DIR) -lrocksdb
+endif
+
+.PHONY: gen_proto clean
+
+# Set PROTOC_BIN when invoking `make` if a custom protoc is required.
+PROTOC_BIN ?= protoc
+
+gen_proto:
+	mkdir -p $(PROTO_OUT)
+	$(PROTOC_BIN) \
+		--proto_path=$(PROTO_IN) \
+		--cpp_out=$(PROTO_OUT) \
+		$(PROTO_IN)/*.proto
+
+clean:
+	rm -rf db_fuzzer db_map_fuzzer sst_file_writer_fuzzer $(PROTO_OUT)
+
+db_fuzzer: db_fuzzer.cc
+	$(CC) $(CCFLAGS) -o db_fuzzer db_fuzzer.cc $(CFLAGS) $(LDFLAGS)
+
+db_map_fuzzer: gen_proto db_map_fuzzer.cc proto/gen/db_operation.pb.cc
+	$(CC) $(CCFLAGS) -o db_map_fuzzer db_map_fuzzer.cc proto/gen/db_operation.pb.cc $(CFLAGS) $(LDFLAGS)
+
+sst_file_writer_fuzzer: gen_proto sst_file_writer_fuzzer.cc proto/gen/db_operation.pb.cc
+	$(CC) $(CCFLAGS) -o sst_file_writer_fuzzer sst_file_writer_fuzzer.cc proto/gen/db_operation.pb.cc $(CFLAGS) $(LDFLAGS)
diff --git a/src/rocksdb/fuzz/README.md b/src/rocksdb/fuzz/README.md
new file mode 100644
index 000000000..238b283a2
--- /dev/null
+++ b/src/rocksdb/fuzz/README.md
@@ -0,0 +1,165 @@
+# Fuzzing RocksDB
+
+## Overview
+
+This directory contains [fuzz tests](https://en.wikipedia.org/wiki/Fuzzing) for RocksDB.
+RocksDB testing infrastructure currently includes unit tests and [stress tests](https://github.com/facebook/rocksdb/wiki/Stress-test),
+we hope fuzz testing can catch more bugs.
+
+## Prerequisite
+
+We use [LLVM libFuzzer](http://llvm.org/docs/LibFuzzer.html) as the fuzzying engine,
+so make sure you have [clang](https://clang.llvm.org/get_started.html) as your compiler.
+
+Some tests rely on [structure aware fuzzing](https://github.com/google/fuzzing/blob/master/docs/structure-aware-fuzzing.md).
+We use [protobuf](https://developers.google.com/protocol-buffers) to define structured input to the fuzzer,
+and use [libprotobuf-mutator](https://github.com/google/libprotobuf-mutator) as the custom libFuzzer mutator.
+So make sure you have protobuf and libprotobuf-mutator installed, and make sure `pkg-config` can find them.
+On some systems, there are both protobuf2 and protobuf3 in the package management system,
+make sure protobuf3 is installed.
+
+If you do not want to install protobuf library yourself, you can rely on libprotobuf-mutator to download protobuf
+for you. For details about installation, please refer to [libprotobuf-mutator README](https://github.com/google/libprotobuf-mutator#readme)
+
+## Example
+
+This example shows you how to do structure aware fuzzing to `rocksdb::SstFileWriter`.
+
+After walking through the steps to create the fuzzer, we'll introduce a bug into `rocksdb::SstFileWriter::Put`,
+then show that the fuzzer can catch the bug.
+
+### Design the test
+
+We want the fuzzing engine to automatically generate a list of database operations,
+then we apply these operations to `SstFileWriter` in sequence,
+finally, after the SST file is generated, we use `SstFileReader` to check the file's checksum.
+
+### Define input
+
+We define the database operations in protobuf, each operation has a type of operation and a key value pair,
+see [proto/db_operation.proto](proto/db_operation.proto) for details.
+
+### Define tests with the input
+
+In [sst_file_writer_fuzzer.cc](sst_file_writer_fuzzer.cc),
+we define the tests to be run on the generated input:
+
+```
+DEFINE_PROTO_FUZZER(DBOperations& input) {
+  // apply the operations to SstFileWriter and use SstFileReader to verify checksum.
+  // ...
+}
+```
+
+`SstFileWriter` requires the keys of the operations to be unique and be in ascending order,
+but the fuzzing engine generates the input randomly, so we need to process the generated input before
+passing it to `DEFINE_PROTO_FUZZER`, this is accomplished by registering a post processor:
+
+```
+protobuf_mutator::libfuzzer::PostProcessorRegistration<DBOperations>
+```
+
+### Compile and link the fuzzer
+
+In the rocksdb root directory, compile rocksdb library by `make static_lib`.
+
+Go to the `fuzz` directory,
+run `make sst_file_writer_fuzzer` to generate the fuzzer,
+it will compile rocksdb static library, generate protobuf, then compile and link `sst_file_writer_fuzzer`.
+
+### Introduce a bug
+
+Manually introduce a bug to `SstFileWriter::Put`:
+
+```
+diff --git a/table/sst_file_writer.cc b/table/sst_file_writer.cc
+index ab1ee7c4e..c7da9ffa0 100644
+--- a/table/sst_file_writer.cc
++++ b/table/sst_file_writer.cc
+@@ -277,6 +277,11 @@ Status SstFileWriter::Add(const Slice& user_key, const Slice& value) {
+ }
+
+ Status SstFileWriter::Put(const Slice& user_key, const Slice& value) {
++  if (user_key.starts_with("!")) {
++    if (value.ends_with("!")) {
++      return Status::Corruption("bomb");
++    }
++  }
+   return rep_->Add(user_key, value, ValueType::kTypeValue);
+ }
+```
+
+The bug is that for `Put`, if `user_key` starts with `!` and `value` ends with `!`, then corrupt.
+
+### Run fuzz testing to catch the bug
+
+Run the fuzzer by `time ./sst_file_writer_fuzzer`.
+
+Here is the output on my machine:
+
+```
+Corruption: bomb
+==59680== ERROR: libFuzzer: deadly signal
+    #0 0x109487315 in __sanitizer_print_stack_trace+0x35 (libclang_rt.asan_osx_dynamic.dylib:x86_64+0x4d315)
+    #1 0x108d63f18 in fuzzer::PrintStackTrace() FuzzerUtil.cpp:205
+    #2 0x108d47613 in fuzzer::Fuzzer::CrashCallback() FuzzerLoop.cpp:232
+    #3 0x7fff6af535fc in _sigtramp+0x1c (libsystem_platform.dylib:x86_64+0x35fc)
+    #4 0x7ffee720f3ef  (<unknown module>)
+    #5 0x7fff6ae29807 in abort+0x77 (libsystem_c.dylib:x86_64+0x7f807)
+    #6 0x108cf1c4c in TestOneProtoInput(DBOperations&)+0x113c (sst_file_writer_fuzzer:x86_64+0x100302c4c)
+    #7 0x108cf09be in LLVMFuzzerTestOneInput+0x16e (sst_file_writer_fuzzer:x86_64+0x1003019be)
+    #8 0x108d48ce0 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) FuzzerLoop.cpp:556
+    #9 0x108d48425 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) FuzzerLoop.cpp:470
+    #10 0x108d4a626 in fuzzer::Fuzzer::MutateAndTestOne() FuzzerLoop.cpp:698
+    #11 0x108d4b325 in fuzzer::Fuzzer::Loop(std::__1::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) FuzzerLoop.cpp:830
+    #12 0x108d37fcd in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) FuzzerDriver.cpp:829
+    #13 0x108d652b2 in main FuzzerMain.cpp:19
+    #14 0x7fff6ad5acc8 in start+0x0 (libdyld.dylib:x86_64+0x1acc8)
+
+NOTE: libFuzzer has rudimentary signal handlers.
+      Combine libFuzzer with AddressSanitizer or similar for better crash reports.
+SUMMARY: libFuzzer: deadly signal
+MS: 7 Custom-CustomCrossOver-InsertByte-Custom-ChangeBit-Custom-CustomCrossOver-; base unit: 90863b4d83c3f994bba0a417d0c2ee3b68f9e795
+0x6f,0x70,0x65,0x72,0x61,0x74,0x69,0x6f,0x6e,0x73,0x20,0x7b,0xa,0x20,0x20,0x6b,0x65,0x79,0x3a,0x20,0x22,0x21,0x22,0xa,0x20,0x20,0x76,0x61,0x6c,0x75,0x65,0x3a,0x20,0x22,0x21,0x22,0xa,0x20,0x20,0x74,0x79,0x70,0x65,0x3a,0x20,0x50,0x55,0x54,0xa,0x7d,0xa,0x6f,0x70,0x65,0x72,0x61,0x74,0x69,0x6f,0x6e,0x73,0x20,0x7b,0xa,0x20,0x20,0x6b,0x65,0x79,0x3a,0x20,0x22,0x2b,0x22,0xa,0x20,0x20,0x74,0x79,0x70,0x65,0x3a,0x20,0x50,0x55,0x54,0xa,0x7d,0xa,0x6f,0x70,0x65,0x72,0x61,0x74,0x69,0x6f,0x6e,0x73,0x20,0x7b,0xa,0x20,0x20,0x6b,0x65,0x79,0x3a,0x20,0x22,0x2e,0x22,0xa,0x20,0x20,0x74,0x79,0x70,0x65,0x3a,0x20,0x50,0x55,0x54,0xa,0x7d,0xa,0x6f,0x70,0x65,0x72,0x61,0x74,0x69,0x6f,0x6e,0x73,0x20,0x7b,0xa,0x20,0x20,0x6b,0x65,0x79,0x3a,0x20,0x22,0x5c,0x32,0x35,0x33,0x22,0xa,0x20,0x20,0x74,0x79,0x70,0x65,0x3a,0x20,0x50,0x55,0x54,0xa,0x7d,0xa,
+operations {\x0a  key: \"!\"\x0a  value: \"!\"\x0a  type: PUT\x0a}\x0aoperations {\x0a  key: \"+\"\x0a  type: PUT\x0a}\x0aoperations {\x0a  key: \".\"\x0a  type: PUT\x0a}\x0aoperations {\x0a  key: \"\\253\"\x0a  type: PUT\x0a}\x0a
+artifact_prefix='./'; Test unit written to ./crash-a1460be302d09b548e61787178d9edaa40aea467
+Base64: b3BlcmF0aW9ucyB7CiAga2V5OiAiISIKICB2YWx1ZTogIiEiCiAgdHlwZTogUFVUCn0Kb3BlcmF0aW9ucyB7CiAga2V5OiAiKyIKICB0eXBlOiBQVVQKfQpvcGVyYXRpb25zIHsKICBrZXk6ICIuIgogIHR5cGU6IFBVVAp9Cm9wZXJhdGlvbnMgewogIGtleTogIlwyNTMiCiAgdHlwZTogUFVUCn0K
+./sst_file_writer_fuzzer  5.97s user 4.40s system 64% cpu 16.195 total
+```
+
+Within 6 seconds, it catches the bug.
+
+The input that triggers the bug is persisted in `./crash-a1460be302d09b548e61787178d9edaa40aea467`:
+
+```
+$ cat ./crash-a1460be302d09b548e61787178d9edaa40aea467
+operations {
+  key: "!"
+  value: "!"
+  type: PUT
+}
+operations {
+  key: "+"
+  type: PUT
+}
+operations {
+  key: "."
+  type: PUT
+}
+operations {
+  key: "\253"
+  type: PUT
+}
+```
+
+### Reproduce the crash to debug
+
+The above crash can be reproduced by `./sst_file_writer_fuzzer ./crash-a1460be302d09b548e61787178d9edaa40aea467`,
+so you can debug the crash.
+
+## Future Work
+
+According to [OSS-Fuzz](https://github.com/google/oss-fuzz),
+`as of June 2020, OSS-Fuzz has found over 20,000 bugs in 300 open source projects.`
+
+RocksDB can join OSS-Fuzz together with other open source projects such as sqlite.
diff --git a/src/rocksdb/fuzz/db_fuzzer.cc b/src/rocksdb/fuzz/db_fuzzer.cc
new file mode 100644
index 000000000..e6d5bb63c
--- /dev/null
+++ b/src/rocksdb/fuzz/db_fuzzer.cc
@@ -0,0 +1,172 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include <fuzzer/FuzzedDataProvider.h>
+
+#include "rocksdb/db.h"
+
+enum OperationType {
+  kPut,
+  kGet,
+  kDelete,
+  kGetProperty,
+  kIterator,
+  kSnapshot,
+  kOpenClose,
+  kColumn,
+  kCompactRange,
+  kSeekForPrev,
+  OP_COUNT
+};
+
+constexpr char db_path[] = "/tmp/testdb";
+
+// Fuzzes DB operations by doing interpretations on the data. Both the
+// sequence of API calls to be called on the DB as well as the arguments
+// to each of these APIs are interpreted by way of the data buffer.
+// The operations that the fuzzer supports are given by the OperationType
+// enum. The goal is to capture sanitizer bugs, so the code should be
+// compiled with a given sanitizer (ASan, UBSan, MSan).
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  ROCKSDB_NAMESPACE::DB* db;
+  ROCKSDB_NAMESPACE::Options options;
+  options.create_if_missing = true;
+  ROCKSDB_NAMESPACE::Status status =
+      ROCKSDB_NAMESPACE::DB::Open(options, db_path, &db);
+  if (!status.ok()) {
+    return 0;
+  }
+  FuzzedDataProvider fuzzed_data(data, size);
+
+  // perform a sequence of calls on our db instance
+  int max_iter = static_cast<int>(data[0]);
+  for (int i = 0; i < max_iter && i < size; i++) {
+    OperationType op = static_cast<OperationType>(data[i] % OP_COUNT);
+
+    switch (op) {
+      case kPut: {
+        std::string key = fuzzed_data.ConsumeRandomLengthString();
+        std::string val = fuzzed_data.ConsumeRandomLengthString();
+        db->Put(ROCKSDB_NAMESPACE::WriteOptions(), key, val);
+        break;
+      }
+      case kGet: {
+        std::string key = fuzzed_data.ConsumeRandomLengthString();
+        std::string value;
+        db->Get(ROCKSDB_NAMESPACE::ReadOptions(), key, &value);
+        break;
+      }
+      case kDelete: {
+        std::string key = fuzzed_data.ConsumeRandomLengthString();
+        db->Delete(ROCKSDB_NAMESPACE::WriteOptions(), key);
+        break;
+      }
+      case kGetProperty: {
+        std::string prop;
+        std::string property_name = fuzzed_data.ConsumeRandomLengthString();
+        db->GetProperty(property_name, &prop);
+        break;
+      }
+      case kIterator: {
+        ROCKSDB_NAMESPACE::Iterator* it =
+            db->NewIterator(ROCKSDB_NAMESPACE::ReadOptions());
+        for (it->SeekToFirst(); it->Valid(); it->Next()) {
+        }
+        delete it;
+        break;
+      }
+      case kSnapshot: {
+        ROCKSDB_NAMESPACE::ReadOptions snapshot_options;
+        snapshot_options.snapshot = db->GetSnapshot();
+        ROCKSDB_NAMESPACE::Iterator* it = db->NewIterator(snapshot_options);
+        db->ReleaseSnapshot(snapshot_options.snapshot);
+        delete it;
+        break;
+      }
+      case kOpenClose: {
+        db->Close();
+        delete db;
+        status = ROCKSDB_NAMESPACE::DB::Open(options, db_path, &db);
+        if (!status.ok()) {
+          ROCKSDB_NAMESPACE::DestroyDB(db_path, options);
+          return 0;
+        }
+
+        break;
+      }
+      case kColumn: {
+        ROCKSDB_NAMESPACE::ColumnFamilyHandle* cf;
+        ROCKSDB_NAMESPACE::Status s;
+        s = db->CreateColumnFamily(ROCKSDB_NAMESPACE::ColumnFamilyOptions(),
+                                   "new_cf", &cf);
+        s = db->DestroyColumnFamilyHandle(cf);
+        db->Close();
+        delete db;
+
+        // open DB with two column families
+        std::vector<ROCKSDB_NAMESPACE::ColumnFamilyDescriptor> column_families;
+        // have to open default column family
+        column_families.push_back(ROCKSDB_NAMESPACE::ColumnFamilyDescriptor(
+            ROCKSDB_NAMESPACE::kDefaultColumnFamilyName,
+            ROCKSDB_NAMESPACE::ColumnFamilyOptions()));
+        // open the new one, too
+        column_families.push_back(ROCKSDB_NAMESPACE::ColumnFamilyDescriptor(
+            "new_cf", ROCKSDB_NAMESPACE::ColumnFamilyOptions()));
+        std::vector<ROCKSDB_NAMESPACE::ColumnFamilyHandle*> handles;
+        s = ROCKSDB_NAMESPACE::DB::Open(ROCKSDB_NAMESPACE::DBOptions(), db_path,
+                                        column_families, &handles, &db);
+
+        if (s.ok()) {
+          std::string key1 = fuzzed_data.ConsumeRandomLengthString();
+          std::string val1 = fuzzed_data.ConsumeRandomLengthString();
+          std::string key2 = fuzzed_data.ConsumeRandomLengthString();
+          s = db->Put(ROCKSDB_NAMESPACE::WriteOptions(), handles[1], key1,
+                      val1);
+          std::string value;
+          s = db->Get(ROCKSDB_NAMESPACE::ReadOptions(), handles[1], key2,
+                      &value);
+          s = db->DropColumnFamily(handles[1]);
+          for (auto handle : handles) {
+            s = db->DestroyColumnFamilyHandle(handle);
+          }
+        } else {
+          status = ROCKSDB_NAMESPACE::DB::Open(options, db_path, &db);
+          if (!status.ok()) {
+            // At this point there is no saving to do. So we exit
+            ROCKSDB_NAMESPACE::DestroyDB(db_path, ROCKSDB_NAMESPACE::Options());
+            return 0;
+          }
+        }
+        break;
+      }
+      case kCompactRange: {
+        std::string slice_start = fuzzed_data.ConsumeRandomLengthString();
+        std::string slice_end = fuzzed_data.ConsumeRandomLengthString();
+
+        ROCKSDB_NAMESPACE::Slice begin(slice_start);
+        ROCKSDB_NAMESPACE::Slice end(slice_end);
+        ROCKSDB_NAMESPACE::CompactRangeOptions options;
+        ROCKSDB_NAMESPACE::Status s = db->CompactRange(options, &begin, &end);
+        break;
+      }
+      case kSeekForPrev: {
+        std::string key = fuzzed_data.ConsumeRandomLengthString();
+        auto iter = db->NewIterator(ROCKSDB_NAMESPACE::ReadOptions());
+        iter->SeekForPrev(key);
+        delete iter;
+        break;
+      }
+      case OP_COUNT:
+        break;
+    }
+  }
+
+  // Cleanup DB
+  db->Close();
+  delete db;
+  ROCKSDB_NAMESPACE::DestroyDB(db_path, options);
+  return 0;
+}
diff --git a/src/rocksdb/fuzz/db_map_fuzzer.cc b/src/rocksdb/fuzz/db_map_fuzzer.cc
new file mode 100644
index 000000000..ed9df8f84
--- /dev/null
+++ b/src/rocksdb/fuzz/db_map_fuzzer.cc
@@ -0,0 +1,107 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <string>
+
+#include "proto/gen/db_operation.pb.h"
+#include "rocksdb/db.h"
+#include "rocksdb/file_system.h"
+#include "src/libfuzzer/libfuzzer_macro.h"
+#include "util.h"
+
+protobuf_mutator::libfuzzer::PostProcessorRegistration<DBOperations> reg = {
+    [](DBOperations* input, unsigned int /* seed */) {
+      const ROCKSDB_NAMESPACE::Comparator* comparator =
+          ROCKSDB_NAMESPACE::BytewiseComparator();
+      auto ops = input->mutable_operations();
+      // Make sure begin <= end for DELETE_RANGE.
+      for (DBOperation& op : *ops) {
+        if (op.type() == OpType::DELETE_RANGE) {
+          auto begin = op.key();
+          auto end = op.value();
+          if (comparator->Compare(begin, end) > 0) {
+            std::swap(begin, end);
+            op.set_key(begin);
+            op.set_value(end);
+          }
+        }
+      }
+    }};
+
+// Execute randomly generated operations on both a DB and a std::map,
+// then reopen the DB and make sure that iterating the DB produces the
+// same key-value pairs as iterating through the std::map.
+DEFINE_PROTO_FUZZER(DBOperations& input) {
+  if (input.operations().empty()) {
+    return;
+  }
+
+  const std::string kDbPath = "/tmp/db_map_fuzzer_test";
+  auto fs = ROCKSDB_NAMESPACE::FileSystem::Default();
+  if (fs->FileExists(kDbPath, ROCKSDB_NAMESPACE::IOOptions(), /*dbg=*/nullptr)
+          .ok()) {
+    std::cerr << "db path " << kDbPath << " already exists" << std::endl;
+    abort();
+  }
+
+  std::map<std::string, std::string> kv;
+  ROCKSDB_NAMESPACE::DB* db = nullptr;
+  ROCKSDB_NAMESPACE::Options options;
+  options.create_if_missing = true;
+  CHECK_OK(ROCKSDB_NAMESPACE::DB::Open(options, kDbPath, &db));
+
+  for (const DBOperation& op : input.operations()) {
+    switch (op.type()) {
+      case OpType::PUT: {
+        CHECK_OK(
+            db->Put(ROCKSDB_NAMESPACE::WriteOptions(), op.key(), op.value()));
+        kv[op.key()] = op.value();
+        break;
+      }
+      case OpType::MERGE: {
+        break;
+      }
+      case OpType::DELETE: {
+        CHECK_OK(db->Delete(ROCKSDB_NAMESPACE::WriteOptions(), op.key()));
+        kv.erase(op.key());
+        break;
+      }
+      case OpType::DELETE_RANGE: {
+        // [op.key(), op.value()) corresponds to [begin, end).
+        CHECK_OK(db->DeleteRange(ROCKSDB_NAMESPACE::WriteOptions(),
+                                 db->DefaultColumnFamily(), op.key(),
+                                 op.value()));
+        kv.erase(kv.lower_bound(op.key()), kv.lower_bound(op.value()));
+        break;
+      }
+      default: {
+        std::cerr << "Unsupported operation" << static_cast<int>(op.type());
+        return;
+      }
+    }
+  }
+  CHECK_OK(db->Close());
+  delete db;
+  db = nullptr;
+
+  CHECK_OK(ROCKSDB_NAMESPACE::DB::Open(options, kDbPath, &db));
+  auto kv_it = kv.begin();
+  ROCKSDB_NAMESPACE::Iterator* it =
+      db->NewIterator(ROCKSDB_NAMESPACE::ReadOptions());
+  for (it->SeekToFirst(); it->Valid(); it->Next(), kv_it++) {
+    CHECK_TRUE(kv_it != kv.end());
+    CHECK_EQ(it->key().ToString(), kv_it->first);
+    CHECK_EQ(it->value().ToString(), kv_it->second);
+  }
+  CHECK_TRUE(kv_it == kv.end());
+  delete it;
+
+  CHECK_OK(db->Close());
+  delete db;
+  CHECK_OK(ROCKSDB_NAMESPACE::DestroyDB(kDbPath, options));
+}
diff --git a/src/rocksdb/fuzz/proto/db_operation.proto b/src/rocksdb/fuzz/proto/db_operation.proto
new file mode 100644
index 000000000..20a55eaa5
--- /dev/null
+++ b/src/rocksdb/fuzz/proto/db_operation.proto
@@ -0,0 +1,28 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+// Defines database operations.
+// Each operation is a key-value pair and an operation type.
+
+syntax = "proto2";
+
+enum OpType {
+  PUT = 0;
+  MERGE = 1;
+  DELETE = 2;
+  DELETE_RANGE = 3;
+}
+
+message DBOperation {
+  required string key = 1;
+  // value is ignored for DELETE.
+  // [key, value] is the range for DELETE_RANGE.
+  optional string value = 2;
+  required OpType type = 3;
+}
+
+message DBOperations {
+  repeated DBOperation operations = 1;
+}
diff --git a/src/rocksdb/fuzz/sst_file_writer_fuzzer.cc b/src/rocksdb/fuzz/sst_file_writer_fuzzer.cc
new file mode 100644
index 000000000..e93b9a3f5
--- /dev/null
+++ b/src/rocksdb/fuzz/sst_file_writer_fuzzer.cc
@@ -0,0 +1,209 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#include <algorithm>
+#include <iostream>
+#include <memory>
+#include <string>
+
+#include "proto/gen/db_operation.pb.h"
+#include "rocksdb/file_system.h"
+#include "rocksdb/sst_file_writer.h"
+#include "src/libfuzzer/libfuzzer_macro.h"
+#include "table/table_builder.h"
+#include "table/table_reader.h"
+#include "util.h"
+
+using ROCKSDB_NAMESPACE::BytewiseComparator;
+using ROCKSDB_NAMESPACE::Comparator;
+using ROCKSDB_NAMESPACE::EnvOptions;
+using ROCKSDB_NAMESPACE::ExternalSstFileInfo;
+using ROCKSDB_NAMESPACE::FileOptions;
+using ROCKSDB_NAMESPACE::FileSystem;
+using ROCKSDB_NAMESPACE::ImmutableCFOptions;
+using ROCKSDB_NAMESPACE::ImmutableOptions;
+using ROCKSDB_NAMESPACE::InternalIterator;
+using ROCKSDB_NAMESPACE::IOOptions;
+using ROCKSDB_NAMESPACE::kMaxSequenceNumber;
+using ROCKSDB_NAMESPACE::Options;
+using ROCKSDB_NAMESPACE::ParsedInternalKey;
+using ROCKSDB_NAMESPACE::ParseInternalKey;
+using ROCKSDB_NAMESPACE::RandomAccessFileReader;
+using ROCKSDB_NAMESPACE::ReadOptions;
+using ROCKSDB_NAMESPACE::SstFileWriter;
+using ROCKSDB_NAMESPACE::Status;
+using ROCKSDB_NAMESPACE::TableReader;
+using ROCKSDB_NAMESPACE::TableReaderCaller;
+using ROCKSDB_NAMESPACE::TableReaderOptions;
+using ROCKSDB_NAMESPACE::ValueType;
+
+// Keys in SST file writer operations must be unique and in ascending order.
+// For each DBOperation generated by the fuzzer, this function is called on
+// it to deduplicate and sort the keys in the DBOperations.
+protobuf_mutator::libfuzzer::PostProcessorRegistration<DBOperations> reg = {
+    [](DBOperations* input, unsigned int /* seed */) {
+      const Comparator* comparator = BytewiseComparator();
+      auto ops = input->mutable_operations();
+
+      // Make sure begin <= end for DELETE_RANGE.
+      for (DBOperation& op : *ops) {
+        if (op.type() == OpType::DELETE_RANGE) {
+          auto begin = op.key();
+          auto end = op.value();
+          if (comparator->Compare(begin, end) > 0) {
+            std::swap(begin, end);
+            op.set_key(begin);
+            op.set_value(end);
+          }
+        }
+      }
+
+      std::sort(ops->begin(), ops->end(),
+                [&comparator](const DBOperation& a, const DBOperation& b) {
+                  return comparator->Compare(a.key(), b.key()) < 0;
+                });
+
+      auto last = std::unique(
+          ops->begin(), ops->end(),
+          [&comparator](const DBOperation& a, const DBOperation& b) {
+            return comparator->Compare(a.key(), b.key()) == 0;
+          });
+      ops->erase(last, ops->end());
+    }};
+
+TableReader* NewTableReader(const std::string& sst_file_path,
+                            const Options& options,
+                            const EnvOptions& env_options,
+                            const ImmutableCFOptions& cf_ioptions) {
+  // This code block is similar to SstFileReader::Open.
+
+  uint64_t file_size = 0;
+  std::unique_ptr<RandomAccessFileReader> file_reader;
+  std::unique_ptr<TableReader> table_reader;
+  const auto& fs = options.env->GetFileSystem();
+  FileOptions fopts(env_options);
+  Status s = options.env->GetFileSize(sst_file_path, &file_size);
+  if (s.ok()) {
+    s = RandomAccessFileReader::Create(fs, sst_file_path, fopts, &file_reader,
+                                       nullptr);
+  }
+  if (s.ok()) {
+    ImmutableOptions iopts(options, cf_ioptions);
+    TableReaderOptions t_opt(iopts, /*prefix_extractor=*/nullptr, env_options,
+                             cf_ioptions.internal_comparator);
+    t_opt.largest_seqno = kMaxSequenceNumber;
+    s = options.table_factory->NewTableReader(t_opt, std::move(file_reader),
+                                              file_size, &table_reader,
+                                              /*prefetch=*/false);
+  }
+  if (!s.ok()) {
+    std::cerr << "Failed to create TableReader for " << sst_file_path << ": "
+              << s.ToString() << std::endl;
+    abort();
+  }
+  return table_reader.release();
+}
+
+ValueType ToValueType(OpType op_type) {
+  switch (op_type) {
+    case OpType::PUT:
+      return ValueType::kTypeValue;
+    case OpType::MERGE:
+      return ValueType::kTypeMerge;
+    case OpType::DELETE:
+      return ValueType::kTypeDeletion;
+    case OpType::DELETE_RANGE:
+      return ValueType::kTypeRangeDeletion;
+    default:
+      std::cerr << "Unknown operation type " << static_cast<int>(op_type)
+                << std::endl;
+      abort();
+  }
+}
+
+// Fuzzes DB operations as input, let SstFileWriter generate a SST file
+// according to the operations, then let TableReader read and check all the
+// key-value pairs from the generated SST file.
+DEFINE_PROTO_FUZZER(DBOperations& input) {
+  if (input.operations().empty()) {
+    return;
+  }
+
+  std::string sstfile;
+  {
+    auto fs = FileSystem::Default();
+    std::string dir;
+    IOOptions opt;
+    CHECK_OK(fs->GetTestDirectory(opt, &dir, nullptr));
+    sstfile = dir + "/SstFileWriterFuzzer.sst";
+  }
+
+  Options options;
+  EnvOptions env_options(options);
+  ImmutableCFOptions cf_ioptions(options);
+
+  // Generate sst file.
+  SstFileWriter writer(env_options, options);
+  CHECK_OK(writer.Open(sstfile));
+  for (const DBOperation& op : input.operations()) {
+    switch (op.type()) {
+      case OpType::PUT: {
+        CHECK_OK(writer.Put(op.key(), op.value()));
+        break;
+      }
+      case OpType::MERGE: {
+        CHECK_OK(writer.Merge(op.key(), op.value()));
+        break;
+      }
+      case OpType::DELETE: {
+        CHECK_OK(writer.Delete(op.key()));
+        break;
+      }
+      case OpType::DELETE_RANGE: {
+        CHECK_OK(writer.DeleteRange(op.key(), op.value()));
+        break;
+      }
+      default: {
+        std::cerr << "Unsupported operation" << static_cast<int>(op.type())
+                  << std::endl;
+        abort();
+      }
+    }
+  }
+  ExternalSstFileInfo info;
+  CHECK_OK(writer.Finish(&info));
+
+  // Iterate and verify key-value pairs.
+  std::unique_ptr<TableReader> table_reader(
+      ::NewTableReader(sstfile, options, env_options, cf_ioptions));
+  ReadOptions roptions;
+  CHECK_OK(table_reader->VerifyChecksum(roptions,
+                                        TableReaderCaller::kUncategorized));
+  std::unique_ptr<InternalIterator> it(
+      table_reader->NewIterator(roptions, /*prefix_extractor=*/nullptr,
+                                /*arena=*/nullptr, /*skip_filters=*/true,
+                                TableReaderCaller::kUncategorized));
+  it->SeekToFirst();
+  for (const DBOperation& op : input.operations()) {
+    if (op.type() == OpType::DELETE_RANGE) {
+      // InternalIterator cannot iterate over DELETE_RANGE entries.
+      continue;
+    }
+    CHECK_TRUE(it->Valid());
+    ParsedInternalKey ikey;
+    CHECK_OK(ParseInternalKey(it->key(), &ikey, /*log_err_key=*/true));
+    CHECK_EQ(ikey.user_key.ToString(), op.key());
+    CHECK_EQ(ikey.sequence, 0);
+    CHECK_EQ(ikey.type, ToValueType(op.type()));
+    if (op.type() != OpType::DELETE) {
+      CHECK_EQ(op.value(), it->value().ToString());
+    }
+    it->Next();
+  }
+  CHECK_TRUE(!it->Valid());
+
+  // Delete sst file.
+  remove(sstfile.c_str());
+}
diff --git a/src/rocksdb/fuzz/util.h b/src/rocksdb/fuzz/util.h
new file mode 100644
index 000000000..97011823a
--- /dev/null
+++ b/src/rocksdb/fuzz/util.h
@@ -0,0 +1,29 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#define CHECK_OK(expression)                       \
+  do {                                             \
+    auto status = (expression);                    \
+    if (!status.ok()) {                            \
+      std::cerr << status.ToString() << std::endl; \
+      abort();                                     \
+    }                                              \
+  } while (0)
+
+#define CHECK_EQ(a, b)                                                      \
+  if (a != b) {                                                             \
+    std::cerr << "(" << #a << "=" << a << ") != (" << #b << "=" << b << ")" \
+              << std::endl;                                                 \
+    abort();                                                                \
+  }
+
+#define CHECK_TRUE(cond)                                      \
+  if (!(cond)) {                                              \
+    std::cerr << "\"" << #cond << "\" is false" << std::endl; \
+    abort();                                                  \
+  }