From 1132333db732548e85c2c860239421b649dcc5d6 Mon Sep 17 00:00:00 2001
From: "A. Unique TensorFlower" <gardener@tensorflow.org>
Date: Mon, 6 Aug 2018 13:19:55 -0700
Subject: Add nullptr checks so that Write() and Flush() fail instead of
 segfault

PiperOrigin-RevId: 207596283
---
 .../core/lib/io/record_reader_writer_test.cc       | 23 ++++++++++++++++++++++
 tensorflow/core/lib/io/record_writer.cc            |  9 +++++++++
 2 files changed, 32 insertions(+)

(limited to 'tensorflow/core/lib')

diff --git a/tensorflow/core/lib/io/record_reader_writer_test.cc b/tensorflow/core/lib/io/record_reader_writer_test.cc
index c36c909399..13bea1f8f1 100644
--- a/tensorflow/core/lib/io/record_reader_writer_test.cc
+++ b/tensorflow/core/lib/io/record_reader_writer_test.cc
@@ -189,4 +189,27 @@ TEST(RecordReaderWriterTest, TestZlib) {
   }
 }
 
+TEST(RecordReaderWriterTest, TestUseAfterClose) {
+  Env* env = Env::Default();
+  string fname = testing::TmpDir() + "/record_reader_writer_flush_close_test";
+
+  {
+    std::unique_ptr<WritableFile> file;
+    TF_CHECK_OK(env->NewWritableFile(fname, &file));
+
+    io::RecordWriterOptions options;
+    options.compression_type = io::RecordWriterOptions::ZLIB_COMPRESSION;
+    io::RecordWriter writer(file.get(), options);
+    TF_EXPECT_OK(writer.WriteRecord("abc"));
+    TF_CHECK_OK(writer.Flush());
+    TF_CHECK_OK(writer.Close());
+
+    CHECK_EQ(writer.WriteRecord("abc").code(), error::FAILED_PRECONDITION);
+    CHECK_EQ(writer.Flush().code(), error::FAILED_PRECONDITION);
+
+    // Second call to close is fine.
+    TF_CHECK_OK(writer.Close());
+  }
+}
+
 }  // namespace tensorflow
diff --git a/tensorflow/core/lib/io/record_writer.cc b/tensorflow/core/lib/io/record_writer.cc
index ebc5648269..6e71d23e71 100644
--- a/tensorflow/core/lib/io/record_writer.cc
+++ b/tensorflow/core/lib/io/record_writer.cc
@@ -93,6 +93,10 @@ static uint32 MaskedCrc(const char* data, size_t n) {
 }
 
 Status RecordWriter::WriteRecord(StringPiece data) {
+  if (dest_ == nullptr) {
+    return Status(::tensorflow::error::FAILED_PRECONDITION,
+                  "Writer not initialized or previously closed");
+  }
   // Format of a single record:
   //  uint64    length
   //  uint32    masked crc of length
@@ -111,6 +115,7 @@ Status RecordWriter::WriteRecord(StringPiece data) {
 }
 
 Status RecordWriter::Close() {
+  if (dest_ == nullptr) return Status::OK();
 #if !defined(IS_SLIM_BUILD)
   if (IsZlibCompressed(options_)) {
     Status s = dest_->Close();
@@ -123,6 +128,10 @@ Status RecordWriter::Close() {
 }
 
 Status RecordWriter::Flush() {
+  if (dest_ == nullptr) {
+    return Status(::tensorflow::error::FAILED_PRECONDITION,
+                  "Writer not initialized or previously closed");
+  }
   if (IsZlibCompressed(options_)) {
     return dest_->Flush();
   }
-- 
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