Fix benign unsigned overflow in AudioTrack
An unsigned overflow could occur in timestamp computation when
mTimestamp < mServer.
Change-Id: I9e01897478a6d481dd6fb7303d325617466497cf
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 735db5c..4a79bef 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -2018,9 +2018,9 @@
// Convert timestamp position from server time base to client time base.
// TODO The following code should work OK now because timestamp.mPosition is 32-bit.
// But if we change it to 64-bit then this could fail.
- // If (mPosition - mServer) can be negative then should use:
- // (int32_t)(mPosition - mServer)
- timestamp.mPosition += mPosition - mServer;
+ // Split this out instead of using += to prevent unsigned overflow
+ // checks in the outer sum.
+ timestamp.mPosition = timestamp.mPosition + static_cast<int32_t>(mPosition) - mServer;
// Immediately after a call to getPosition_l(), mPosition and
// mServer both represent the same frame position. mPosition is
// in client's point of view, and mServer is in server's point of