diff --git a/drm/1.0/default/CryptoPlugin.cpp b/drm/1.0/default/CryptoPlugin.cpp
index e6d4e84..de8bbd5 100644
--- a/drm/1.0/default/CryptoPlugin.cpp
+++ b/drm/1.0/default/CryptoPlugin.cpp
@@ -53,6 +53,8 @@
             uint32_t bufferId) {
         sp<IMemory> hidlMemory = mapMemory(base);
 
+        std::lock_guard<std::mutex> shared_buffer_lock(mSharedBufferLock);
+
         // allow mapMemory to return nullptr
         mSharedBufferMap[bufferId] = hidlMemory;
         return Void();
@@ -65,7 +67,7 @@
             const SharedBuffer& source, uint64_t offset,
             const DestinationBuffer& destination,
             decrypt_cb _hidl_cb) {
-
+        std::unique_lock<std::mutex> shared_buffer_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();
@@ -79,7 +81,7 @@
             }
         }
 
-        android::CryptoPlugin::Mode legacyMode;
+        android::CryptoPlugin::Mode legacyMode = android::CryptoPlugin::kMode_Unencrypted;
         switch(mode) {
         case Mode::UNENCRYPTED:
             legacyMode = android::CryptoPlugin::kMode_Unencrypted;
@@ -170,6 +172,10 @@
             _hidl_cb(Status::BAD_VALUE, 0, "invalid destination type");
             return Void();
         }
+
+        // release mSharedBufferLock
+        shared_buffer_lock.unlock();
+
         ssize_t result = mLegacyPlugin->decrypt(secure, keyId.data(), iv.data(),
                 legacyMode, legacyPattern, srcPtr, legacySubSamples.get(),
                 subSamples.size(), destPtr, &detailMessage);