Re: "Truncated" tuples for tuple hash tables

["Bort, Paul" <pbort(at)tmwsystems(dot)com>]

Tom Lane said:
> 
> To make use of a TruncatedTuple, we'd set up a temporary HeapTupleData
> struct with its t_data field pointing 16 bytes before the start of the
> TruncatedTuple.  As long as the code using it never tries to 
> access any
> of the missing fields (t_xmin through t_ctid), this would work exactly
> like a normal HeapTuple.
> 

This sounds like a security risk. What's the worst thing that could be
in
those 16 bytes, and could that be used to bite (sorry) us? 

If those 16 bytes could be user data in another tuple, there might be an
attack there.