fix(storage): add mutex around uses of mrd variables (#11405)

storage/grpc_client.go

@@ -1190,7 +1190,9 @@ func (c *grpcStorageClient) NewMultiRangeDownloader(ctx context.Context, params
 		for {
 			select {
 			case <-rr.ctx.Done():
+				rr.mu.Lock()
 				rr.done = true
+				rr.mu.Unlock()
 				return
 			case <-rr.managerRetry:
 				return
@@ -1349,7 +1351,9 @@ func (c *grpcStorageClient) NewMultiRangeDownloader(ctx context.Context, params
 		rr.mu.Unlock()
 	}
 
+	rr.mu.Lock()
 	rr.objectSize = size
+	rr.mu.Unlock()
 
 	go streamManager()
 	go streamReceiver()
@@ -1424,8 +1428,12 @@ func (r *gRPCBidiReader) reopenStream(failSpec []rangeSpec) error {
 
 // Add will add current range to stream.
 func (mr *gRPCBidiReader) add(output io.Writer, offset, limit int64, callback func(int64, int64, error)) {
-	if offset > mr.objectSize {
-		callback(offset, limit, fmt.Errorf("offset larger than size of object: %v", mr.objectSize))
+	mr.mu.Lock()
+	objectSize := mr.objectSize
+	mr.mu.Unlock()
+
+	if offset > objectSize {
+		callback(offset, limit, fmt.Errorf("offset larger than size of object: %v", objectSize))
 		return
 	}
 	if limit < 0 {
@@ -1463,8 +1471,10 @@ func (mr *gRPCBidiReader) close() error {
 	if mr.cancel != nil {
 		mr.cancel()
 	}
+	mr.mu.Lock()
 	mr.done = true
 	mr.activeTask = 0
+	mr.mu.Unlock()
 	mr.closeReceiver <- true
 	mr.closeManager <- true
 	return nil
@@ -1877,11 +1887,11 @@ type gRPCBidiReader struct {
 	closeManager     chan bool
 	managerRetry     chan bool
 	receiverRetry    chan bool
+	mu               sync.Mutex          // protects all vars in gRPCBidiReader from concurrent access
 	mp               map[int64]rangeSpec // always use the mutex when accessing the map
-	mu               sync.Mutex          // protects map from concurrent access.
-	done             bool
-	activeTask       int64
-	objectSize       int64
+	done             bool                // always use the mutex when accessing this variable
+	activeTask       int64               // always use the mutex when accessing this variable
+	objectSize       int64               // always use the mutex when accessing this variable
 	retrier          func(error, string)
 	streamRecreation bool // This helps us identify if stream recreation is in progress or not. If stream recreation gets called from two goroutine then this will stop second one.
 }