Merge "Fix WVCryptoPlugin use after free vulnerability." into sc-dev am: 9d1ad7590a

Original change: https://googleplex-android-review.googlesource.com/c/platform/vendor/widevine/+/13808139

Change-Id: I4c2aadb7b98c48abc349582d0bca0ddb41d05df7

libwvdrmengine/mediacrypto/src_hidl/WVCryptoPlugin.cpp

@@ -121,6 +121,8 @@ Return<void> WVCryptoPlugin::setSharedBufferBase(
     const hidl_memory& base, 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();
@@ -169,7 +171,7 @@ Return<void> WVCryptoPlugin::decrypt_1_2(
     uint64_t offset,
     const DestinationBuffer& destination,
     decrypt_1_2_cb _hidl_cb) {
-
+  std::unique_lock<std::mutex> 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");
@@ -245,6 +247,9 @@ Return<void> WVCryptoPlugin::decrypt_1_2(
     destPtr = static_cast<void *>(handle);
   }
 
+  // release mSharedBufferLock
+  lock.unlock();
+
   // Set up the decrypt params
   CdmDecryptionParametersV16 params;
   params.key_id = cryptoKey;