diff --git a/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp b/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
index 005e551..302dd39 100644
--- a/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
+++ b/drm/mediadrm/plugins/clearkey/hidl/CryptoPlugin.cpp
@@ -37,6 +37,8 @@
     sp<IMemory> hidlMemory = mapMemory(base);
     ALOGE_IF(hidlMemory == nullptr, "mapMemory returns nullptr");
 
+    std::lock_guard<std::mutex> shared_buffer_lock(mSharedBufferLock);
+
     // allow mapMemory to return nullptr
     mSharedBufferMap[bufferId] = hidlMemory;
     return Void();
@@ -94,6 +96,7 @@
         return Void();
     }
 
+    std::unique_lock<std::mutex> shared_buffer_lock(mSharedBufferLock);
     if (mSharedBufferMap.find(source.bufferId) == mSharedBufferMap.end()) {
       _hidl_cb(Status_V1_2::ERROR_DRM_CANNOT_HANDLE, 0,
                "source decrypt buffer base not set");
@@ -151,6 +154,9 @@
     }
     destPtr = static_cast<void*>(base + destination.nonsecureMemory.offset);
 
+    // release mSharedBufferLock
+    shared_buffer_lock.unlock();
+
     // Calculate the output buffer size and determine if any subsamples are
     // encrypted.
     size_t destSize = 0;
diff --git a/drm/mediadrm/plugins/clearkey/hidl/include/CryptoPlugin.h b/drm/mediadrm/plugins/clearkey/hidl/include/CryptoPlugin.h
index 8680f0c..23a64fa 100644
--- a/drm/mediadrm/plugins/clearkey/hidl/include/CryptoPlugin.h
+++ b/drm/mediadrm/plugins/clearkey/hidl/include/CryptoPlugin.h
@@ -20,6 +20,8 @@
 #include <android/hardware/drm/1.2/ICryptoPlugin.h>
 #include <android/hidl/memory/1.0/IMemory.h>
 
+#include <mutex>
+
 #include "ClearKeyTypes.h"
 #include "Session.h"
 #include "Utils.h"
@@ -93,7 +95,7 @@
             const SharedBuffer& source,
             uint64_t offset,
             const DestinationBuffer& destination,
-            decrypt_1_2_cb _hidl_cb);
+            decrypt_1_2_cb _hidl_cb) NO_THREAD_SAFETY_ANALYSIS; // use unique_lock
 
     Return<void> setSharedBufferBase(const hidl_memory& base,
             uint32_t bufferId);
@@ -105,7 +107,8 @@
 private:
     CLEARKEY_DISALLOW_COPY_AND_ASSIGN(CryptoPlugin);
 
-    std::map<uint32_t, sp<IMemory> > mSharedBufferMap;
+    std::mutex mSharedBufferLock;
+    std::map<uint32_t, sp<IMemory>> mSharedBufferMap GUARDED_BY(mSharedBufferLock);
     sp<Session> mSession;
     Status mInitStatus;
 };