Add overflow checks in Memory objects.

Also change one of the reads to be explicitly ReadField instead of an
overloaded Read function.

Bug: 23762183

Test: Passes new unit tests.
Change-Id: Id848f7b632f67df0c5b7318d9e588942cfd2099a

1 files changed, 27 insertions, 30 deletions

diff --git a/libunwindstack/tests/MemoryFileTest.cpp b/libunwindstack/tests/MemoryFileTest.cpp
index 870ca19d2..aa7a23a34 100644
--- a/libunwindstack/tests/MemoryFileTest.cpp
+++ b/libunwindstack/tests/MemoryFileTest.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#include <string>
+#include <vector>
+
 #include <android-base/test_utils.h>
 #include <android-base/file.h>
 #include <gtest/gtest.h>
@@ -39,7 +42,7 @@ class MemoryFileTest : public ::testing::Test {
   TemporaryFile* tf_ = nullptr;
 };
 
-TEST_F(MemoryFileTest, offset_0) {
+TEST_F(MemoryFileTest, init_offset_0) {
   WriteTestData();
 
   ASSERT_TRUE(memory_.Init(tf_->path, 0));
@@ -49,7 +52,7 @@ TEST_F(MemoryFileTest, offset_0) {
   ASSERT_STREQ("0123456789", buffer.data());
 }
 
-TEST_F(MemoryFileTest, offset_non_zero) {
+TEST_F(MemoryFileTest, init_offset_non_zero) {
   WriteTestData();
 
   ASSERT_TRUE(memory_.Init(tf_->path, 10));
@@ -59,7 +62,7 @@ TEST_F(MemoryFileTest, offset_non_zero) {
   ASSERT_STREQ("abcdefghij", buffer.data());
 }
 
-TEST_F(MemoryFileTest, offset_non_zero_larger_than_pagesize) {
+TEST_F(MemoryFileTest, init_offset_non_zero_larger_than_pagesize) {
   size_t pagesize = getpagesize();
   std::string large_string;
   for (size_t i = 0; i < pagesize; i++) {
@@ -75,7 +78,7 @@ TEST_F(MemoryFileTest, offset_non_zero_larger_than_pagesize) {
   ASSERT_STREQ("abcdefgh", buffer.data());
 }
 
-TEST_F(MemoryFileTest, offset_pagesize_aligned) {
+TEST_F(MemoryFileTest, init_offset_pagesize_aligned) {
   size_t pagesize = getpagesize();
   std::string data;
   for (size_t i = 0; i < 2 * pagesize; i++) {
@@ -96,7 +99,7 @@ TEST_F(MemoryFileTest, offset_pagesize_aligned) {
   ASSERT_STREQ(expected_str.c_str(), buffer.data());
 }
 
-TEST_F(MemoryFileTest, offset_pagesize_aligned_plus_extra) {
+TEST_F(MemoryFileTest, init_offset_pagesize_aligned_plus_extra) {
   size_t pagesize = getpagesize();
   std::string data;
   for (size_t i = 0; i < 2 * pagesize; i++) {
@@ -117,6 +120,23 @@ TEST_F(MemoryFileTest, offset_pagesize_aligned_plus_extra) {
   ASSERT_STREQ(expected_str.c_str(), buffer.data());
 }
 
+TEST_F(MemoryFileTest, init_offset_greater_than_filesize) {
+  size_t pagesize = getpagesize();
+  std::string data;
+  uint64_t file_size = 2 * pagesize + pagesize / 2;
+  for (size_t i = 0; i < file_size; i++) {
+    data += static_cast<char>((i / pagesize) + '0');
+  }
+  ASSERT_TRUE(android::base::WriteStringToFd(data, tf_->fd));
+
+  // Check offset > file size fails and aligned_offset > file size.
+  ASSERT_FALSE(memory_.Init(tf_->path, file_size + 2 * pagesize));
+  // Check offset == filesize fails.
+  ASSERT_FALSE(memory_.Init(tf_->path, file_size));
+  // Check aligned_offset < filesize, but offset > filesize fails.
+  ASSERT_FALSE(memory_.Init(tf_->path, 2 * pagesize + pagesize / 2 + pagesize / 4));
+}
+
 TEST_F(MemoryFileTest, read_error) {
   std::string data;
   for (size_t i = 0; i < 5000; i++) {
@@ -137,32 +157,9 @@ TEST_F(MemoryFileTest, read_error) {
   ASSERT_TRUE(memory_.Read(4990, buffer.data(), 10));
   ASSERT_FALSE(memory_.Read(4999, buffer.data(), 2));
   ASSERT_TRUE(memory_.Read(4999, buffer.data(), 1));
-}
-
-TEST_F(MemoryFileTest, read_string) {
-  std::string value("name_in_file");
-  ASSERT_TRUE(android::base::WriteFully(tf_->fd, value.c_str(), value.size() + 1));
-
-  std::string name;
-  ASSERT_TRUE(memory_.Init(tf_->path, 0));
-  ASSERT_TRUE(memory_.ReadString(0, &name));
-  ASSERT_EQ("name_in_file", name);
-  ASSERT_TRUE(memory_.ReadString(5, &name));
-  ASSERT_EQ("in_file", name);
-}
-
-TEST_F(MemoryFileTest, read_string_error) {
-  std::vector<uint8_t> buffer = { 0x23, 0x32, 0x45 };
-  ASSERT_TRUE(android::base::WriteFully(tf_->fd, buffer.data(), buffer.size()));
-
-  std::string name;
-  ASSERT_TRUE(memory_.Init(tf_->path, 0));
-
-  // Read from a non-existant address.
-  ASSERT_FALSE(memory_.ReadString(100, &name));
 
-  // This should fail because there is no terminating \0
-  ASSERT_FALSE(memory_.ReadString(0, &name));
+  // Check that overflow fails properly.
+  ASSERT_FALSE(memory_.Read(UINT64_MAX - 100, buffer.data(), 200));
 }
 
 TEST_F(MemoryFileTest, read_past_file_within_mapping) {