diff --git a/drm/1.0/default/Android.bp b/drm/1.0/default/Android.bp
index ed6bcde..1122e46 100644
--- a/drm/1.0/default/Android.bp
+++ b/drm/1.0/default/Android.bp
@@ -9,6 +9,7 @@
         "-Werror",
         "-Wextra",
         "-Wall",
+        "-Wthread-safety",
     ],
     shared_libs: [
         "liblog",
@@ -19,5 +20,5 @@
     export_header_lib_headers: [
         "libutils_headers",
     ],
-    export_include_dirs : ["include"]
+    export_include_dirs: ["include"],
 }
diff --git a/drm/1.0/default/CryptoPlugin.cpp b/drm/1.0/default/CryptoPlugin.cpp
index 2a85f0e..74047ff 100644
--- a/drm/1.0/default/CryptoPlugin.cpp
+++ b/drm/1.0/default/CryptoPlugin.cpp
@@ -54,6 +54,8 @@
         sp<IMemory> hidlMemory = mapMemory(base);
         ALOGE_IF(hidlMemory == nullptr, "mapMemory returns nullptr");
 
+        std::unique_lock<std::mutex> lock(mSharedBufferLock);
+
         // allow mapMemory to return nullptr
         mSharedBufferMap[bufferId] = hidlMemory;
         return Void();
@@ -66,7 +68,7 @@
             const SharedBuffer& source, uint64_t offset,
             const DestinationBuffer& destination,
             decrypt_cb _hidl_cb) {
-
+        std::unique_lock<std::mutex> lock(mSharedBufferLock);
         if (mSharedBufferMap.find(source.bufferId) == mSharedBufferMap.end()) {
             _hidl_cb(Status::ERROR_DRM_CANNOT_HANDLE, 0, "source decrypt buffer base not set");
             return Void();
@@ -80,7 +82,7 @@
             }
         }
 
-        android::CryptoPlugin::Mode legacyMode;
+        android::CryptoPlugin::Mode legacyMode = android::CryptoPlugin::kMode_Unencrypted;
         switch(mode) {
         case Mode::UNENCRYPTED:
             legacyMode = android::CryptoPlugin::kMode_Unencrypted;
@@ -176,6 +178,9 @@
             _hidl_cb(Status::BAD_VALUE, 0, "invalid destination type");
             return Void();
         }
+
+        // release mSharedBufferLock
+        lock.unlock();
         ssize_t result = mLegacyPlugin->decrypt(secure, keyId.data(), iv.data(),
                 legacyMode, legacyPattern, srcPtr, legacySubSamples,
                 subSamples.size(), destPtr, &detailMessage);
diff --git a/drm/1.0/default/CryptoPlugin.h b/drm/1.0/default/CryptoPlugin.h
index 11cc2aa..13fe898 100644
--- a/drm/1.0/default/CryptoPlugin.h
+++ b/drm/1.0/default/CryptoPlugin.h
@@ -17,11 +17,14 @@
 #ifndef ANDROID_HARDWARE_DRM_V1_0__CRYPTOPLUGIN_H
 #define ANDROID_HARDWARE_DRM_V1_0__CRYPTOPLUGIN_H
 
-#include <android/hidl/memory/1.0/IMemory.h>
+#include <android-base/thread_annotations.h>
 #include <android/hardware/drm/1.0/ICryptoPlugin.h>
+#include <android/hidl/memory/1.0/IMemory.h>
 #include <hidl/Status.h>
 #include <media/hardware/CryptoAPI.h>
 
+#include <mutex>
+
 namespace android {
 namespace hardware {
 namespace drm {
@@ -60,19 +63,21 @@
     Return<void> setSharedBufferBase(const ::android::hardware::hidl_memory& base,
         uint32_t bufferId) override;
 
-    Return<void> decrypt(bool secure, const hidl_array<uint8_t, 16>& keyId,
-            const hidl_array<uint8_t, 16>& iv, Mode mode, const Pattern& pattern,
-            const hidl_vec<SubSample>& subSamples, const SharedBuffer& source,
-            uint64_t offset, const DestinationBuffer& destination,
-            decrypt_cb _hidl_cb) override;
+    Return<void> decrypt(
+        bool secure, const hidl_array<uint8_t, 16>& keyId, const hidl_array<uint8_t, 16>& iv,
+        Mode mode, const Pattern& pattern, const hidl_vec<SubSample>& subSamples,
+        const SharedBuffer& source, uint64_t offset, const DestinationBuffer& destination,
+        decrypt_cb _hidl_cb) override NO_THREAD_SAFETY_ANALYSIS;  // use unique_lock
 
-private:
+   private:
     android::CryptoPlugin *mLegacyPlugin;
-    std::map<uint32_t, sp<IMemory> > mSharedBufferMap;
+    std::map<uint32_t, sp<IMemory>> mSharedBufferMap GUARDED_BY(mSharedBufferLock);
 
     CryptoPlugin() = delete;
     CryptoPlugin(const CryptoPlugin &) = delete;
     void operator=(const CryptoPlugin &) = delete;
+
+    std::mutex mSharedBufferLock;
 };
 
 }  // namespace implementation