diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 597d057..ac672a7 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -138,6 +138,11 @@
       mPreviousPriority(ANDROID_PRIORITY_NORMAL),
       mPreviousSchedulingGroup(SP_DEFAULT)
 {
+    if (sharedBuffer == 0) {
+        ALOGE("sharedBuffer must be non-0");
+        mStatus = BAD_VALUE;
+        return;
+    }
     mStatus = set(streamType, sampleRate, format, channelMask,
             0 /*frameCount*/, flags, cbf, user, notificationFrames,
             sharedBuffer, false /*threadCanCallJava*/, sessionId);
@@ -535,6 +540,10 @@
 // must be called with mLock held
 status_t AudioTrack::setLoop_l(uint32_t loopStart, uint32_t loopEnd, int loopCount)
 {
+    if (mSharedBuffer == 0 || mIsTimed) {
+        return INVALID_OPERATION;
+    }
+
     audio_track_cblk_t* cblk = mCblk;
 
     Mutex::Autolock _l(cblk->lock);
@@ -547,10 +556,6 @@
         return NO_ERROR;
     }
 
-    if (mIsTimed) {
-        return INVALID_OPERATION;
-    }
-
     if (loopStart >= loopEnd ||
         loopEnd - loopStart > mFrameCount ||
         cblk->server > loopStart) {
@@ -624,7 +629,7 @@
 
 status_t AudioTrack::setPosition(uint32_t position)
 {
-    if (mIsTimed) {
+    if (mSharedBuffer == 0 || mIsTimed) {
         return INVALID_OPERATION;
     }
 
@@ -660,6 +665,10 @@
 
 status_t AudioTrack::reload()
 {
+    if (mSharedBuffer == 0 || mIsTimed) {
+        return INVALID_OPERATION;
+    }
+
     AutoMutex lock(mLock);
 
     if (!stopped_l()) {
@@ -1036,10 +1045,7 @@
 ssize_t AudioTrack::write(const void* buffer, size_t userSize)
 {
 
-    if (mSharedBuffer != 0) {
-        return INVALID_OPERATION;
-    }
-    if (mIsTimed) {
+    if (mSharedBuffer != 0 || mIsTimed) {
         return INVALID_OPERATION;
     }