Re: [HACKERS] Buffer overuns with the Electric fence debugging library - Mailing list pgsql-hackers

From darrenk@insightdist.com (Darren King)
Subject Re: [HACKERS] Buffer overuns with the Electric fence debugging library
Date
Msg-id 9803181539.AA64488@ceodev
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List pgsql-hackers
>
> The errors are all found in the DataFill function called from
> heap_from_tuple.
>

Where specifically in DataFill?

>
> Do you guys feel comfortable with a database which has reproducible
> buffer overuns?
>
> I think it would be great is somebody who has more experience with
> postgresql than I were to look at this.
>

This might be by design.  Check out include/access/htup.h and look at
how the tuple is defined.  Basically, there is a struct with the
necessary header fields that is used to cast an area of memory that
has been [p]alloc'd.  See heap_addheader as an example...

Note that this technique has been declared as "Bad" by the C standards
committee, but it works and there are other things more broken.

darrenk

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