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Commit 20b82e0c authored by Chad Brubaker's avatar Chad Brubaker
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Fix benign unsigned overflow in AudioTrack 

An unsigned overflow could occur in timestamp computation when
mTimestamp < mServer.

Change-Id: I9e01897478a6d481dd6fb7303d325617466497cf
parent 318dd9b8

media/libmedia/AudioTrack.cpp

+3 −3
Original line number Diff line number Diff line
@@ -2018,9 +2018,9 @@ status_t AudioTrack::getTimestamp(AudioTimestamp& timestamp) 
        // 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