*** a/src/backend/access/gin/ginentrypage.c
--- b/src/backend/access/gin/ginentrypage.c
***************
*** 112,117 **** GinFormTuple(GinState *ginstate,
--- 112,123 ----
  	if (newsize != IndexTupleSize(itup))
  	{
  		itup = repalloc(itup, newsize);
+ 		/*
+ 		 * PostgreSQL 9.3 and earlier did not clear this new space, so we
+ 		 * might find uninitialized padding when reading tuples from disk.
+ 		 */
+ 		memset((char *) itup + IndexTupleSize(itup),
+ 			   0, newsize - IndexTupleSize(itup));
  
  		/* set new size in tuple header */
  		itup->t_info &= ~INDEX_SIZE_MASK;