diff --git a/graphics/mapper/4.0/IMapper.hal b/graphics/mapper/4.0/IMapper.hal
index 85c7c81..46506f5 100644
--- a/graphics/mapper/4.0/IMapper.hal
+++ b/graphics/mapper/4.0/IMapper.hal
@@ -219,7 +219,8 @@
      *     - `BAD_BUFFER` if the buffer is invalid or is incompatible with this
      *       function.
      *     - `BAD_VALUE` if @p cpuUsage is 0, contains non-CPU usage flags, or
-     *       is incompatible with the buffer.
+     *       is incompatible with the buffer. Also if the @p accessRegion is
+     *       outside the bounds of the buffer or the accessRegion is invalid.
      *     - `NO_RESOURCES` if the buffer cannot be locked at this time. Note
      *       that locking may succeed at a later time.
      * @return data CPU-accessible pointer to the buffer data.
diff --git a/graphics/mapper/4.0/vts/functional/VtsHalGraphicsMapperV4_0TargetTest.cpp b/graphics/mapper/4.0/vts/functional/VtsHalGraphicsMapperV4_0TargetTest.cpp
index 706c658..ef7a626 100644
--- a/graphics/mapper/4.0/vts/functional/VtsHalGraphicsMapperV4_0TargetTest.cpp
+++ b/graphics/mapper/4.0/vts/functional/VtsHalGraphicsMapperV4_0TargetTest.cpp
@@ -404,6 +404,49 @@
 }
 
 /**
+ * Test IMapper::unlock with bad access region
+ */
+TEST_F(GraphicsMapperHidlTest, LockBadAccessRegion) {
+    const auto& info = mDummyDescriptorInfo;
+
+    const native_handle_t* bufferHandle;
+    ASSERT_NO_FATAL_FAILURE(bufferHandle = mGralloc->allocate(info, true));
+
+    const IMapper::Rect accessRegion{0, 0, static_cast<int32_t>(info.width * 2),
+                                     static_cast<int32_t>(info.height * 2)};
+    int acquireFence = -1;
+
+    NATIVE_HANDLE_DECLARE_STORAGE(acquireFenceStorage, 1, 0);
+    hidl_handle acquireFenceHandle;
+    if (acquireFence >= 0) {
+        auto h = native_handle_init(acquireFenceStorage, 1, 0);
+        h->data[0] = acquireFence;
+        acquireFenceHandle = h;
+    }
+
+    auto buffer = const_cast<native_handle_t*>(bufferHandle);
+    mGralloc->getMapper()->lock(buffer, info.usage, accessRegion, acquireFenceHandle,
+                                [&](const auto& tmpError, const auto& /*tmpData*/,
+                                    int32_t /*tmpBytesPerPixel*/, int32_t /*tmpBytesPerStride*/) {
+                                    EXPECT_EQ(Error::BAD_VALUE, tmpError)
+                                            << "locking with a bad access region should fail";
+                                });
+
+    if (::testing::Test::HasFailure()) {
+        if (acquireFence >= 0) {
+            close(acquireFence);
+        }
+
+        int releaseFence = -1;
+        ASSERT_NO_FATAL_FAILURE(releaseFence = mGralloc->unlock(bufferHandle));
+
+        if (releaseFence >= 0) {
+            close(releaseFence);
+        }
+    }
+}
+
+/**
  * Test IMapper::unlock with invalid buffers.
  */
 TEST_F(GraphicsMapperHidlTest, UnlockNegative) {