diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index d5def48..7308c41 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -6528,6 +6528,7 @@
         rear = mRsmpInRear += framesRead;
 
         size = activeTracks.size();
+
         // loop over each active track
         for (size_t i = 0; i < size; i++) {
             activeTrack = activeTracks[i];
@@ -6584,6 +6585,11 @@
                 if (activeTrack->mFramesToDrop == 0) {
                     if (framesOut > 0) {
                         activeTrack->mSink.frameCount = framesOut;
+                        // Sanitize before releasing if the track has no access to the source data
+                        // An idle UID receives silence from non virtual devices until active
+                        if (activeTrack->isSilenced()) {
+                            memset(activeTrack->mSink.raw, 0, framesOut * mFrameSize);
+                        }
                         activeTrack->releaseBuffer(&activeTrack->mSink);
                     }
                 } else {
@@ -6923,7 +6929,9 @@
         status_t status = NO_ERROR;
         if (recordTrack->isExternalTrack()) {
             mLock.unlock();
-            status = AudioSystem::startInput(mId, recordTrack->sessionId());
+            bool silenced;
+            status = AudioSystem::startInput(mId, recordTrack->sessionId(),
+                    mInDevice, recordTrack->uid(), &silenced);
             mLock.lock();
             // FIXME should verify that recordTrack is still in mActiveTracks
             if (status != NO_ERROR) {
@@ -6932,6 +6940,7 @@
                 ALOGV("RecordThread::start error %d", status);
                 return status;
             }
+            recordTrack->setSilenced(silenced);
         }
         // Catch up with current buffer indices if thread is already running.
         // This is what makes a new client discard all buffered data.  If the track's mRsmpInFront
@@ -7135,6 +7144,16 @@
     write(fd, result.string(), result.size());
 }
 
+void AudioFlinger::RecordThread::setRecordSilenced(uid_t uid, bool silenced)
+{
+    Mutex::Autolock _l(mLock);
+    for (size_t i = 0; i < mTracks.size() ; i++) {
+        sp<RecordTrack> track = mTracks[i];
+        if (track != 0 && track->uid() == uid) {
+            track->setSilenced(silenced);
+        }
+    }
+}
 
 void AudioFlinger::RecordThread::ResamplerBufferProvider::reset()
 {
@@ -7827,7 +7846,9 @@
     if (isOutput()) {
         ret = AudioSystem::startOutput(mId, streamType(), mSessionId);
     } else {
-        ret = AudioSystem::startInput(mId, mSessionId);
+        // TODO: Block recording for idle UIDs (b/72134552)
+        bool silenced;
+        ret = AudioSystem::startInput(mId, mSessionId, mInDevice, client.clientUid, &silenced);
     }
 
     // abort if start is rejected by audio policy manager