Bug 1832832 - protect encoder accesses in Java callbacks. r=media-playback-reviewers,alwu a=pascalc

Differential Revision: https://phabricator.services.mozilla.com/D178564

dom/media/platforms/android/AndroidDataEncoder.cpp

@@ -494,7 +494,10 @@ void AndroidDataEncoder<ConfigType>::CallbacksSupport::HandleInput(
 template <typename ConfigType>
 void AndroidDataEncoder<ConfigType>::CallbacksSupport::HandleOutput(
     java::Sample::Param aSample, java::SampleBuffer::Param aBuffer) {
-  mEncoder->ProcessOutput(std::move(aSample), std::move(aBuffer));
+  MutexAutoLock lock(mMutex);
+  if (mEncoder) {
+    mEncoder->ProcessOutput(std::move(aSample), std::move(aBuffer));
+  }
 }
 
 template <typename ConfigType>
@@ -504,7 +507,10 @@ void AndroidDataEncoder<ConfigType>::CallbacksSupport::
 template <typename ConfigType>
 void AndroidDataEncoder<ConfigType>::CallbacksSupport::HandleError(
     const MediaResult& aError) {
-  mEncoder->Error(aError);
+  MutexAutoLock lock(mMutex);
+  if (mEncoder) {
+    mEncoder->Error(aError);
+  }
 }
 
 // Force compiler to generate code.

dom/media/platforms/android/AndroidDataEncoder.h

@@ -13,6 +13,7 @@
 
 #include "mozilla/Maybe.h"
 #include "mozilla/Monitor.h"
+#include "mozilla/Mutex.h"
 
 namespace mozilla {
 
@@ -36,7 +37,15 @@ class AndroidDataEncoder final : public MediaDataEncoder {
   class CallbacksSupport final : public JavaCallbacksSupport {
    public:
     explicit CallbacksSupport(AndroidDataEncoder* aEncoder)
-        : mEncoder(aEncoder) {}
+        : mMutex("AndroidDataEncoder::CallbacksSupport") {
+      MutexAutoLock lock(mMutex);
+      mEncoder = aEncoder;
+    }
+
+    ~CallbacksSupport() {
+      MutexAutoLock lock(mMutex);
+      mEncoder = nullptr;
+    }
 
     void HandleInput(int64_t aTimestamp, bool aProcessed) override;
     void HandleOutput(java::Sample::Param aSample,
@@ -46,7 +55,8 @@ class AndroidDataEncoder final : public MediaDataEncoder {
     void HandleError(const MediaResult& aError) override;
 
    private:
-    AndroidDataEncoder* mEncoder;
+    Mutex mMutex;
+    AndroidDataEncoder* mEncoder MOZ_GUARDED_BY(mMutex);
   };
   friend class CallbacksSupport;