Re: BUG #14134: segmentation fault with large table with gist index

On Wed, May 11, 2016 at 12:56 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> Consider that most types have SortSupport, and so will use their own
> memory context if memory allocation is needed for nodeIndexScan.c's
> new-to-9.5 sort-like merging involving SortSupport. The field
> ssup_collation was also not correctly initialized, for example, but
> the SortSupport was allocated with palloc0(), so any problems that
> that causes for collatable types will be relatively subtle. According
> to convention, we won't attempt allocation with the ssup_ctx "parent"
> memory context (which is NULL here), or we won't allocate any memory
> at all in the case of simple pass-by-value types like int4.

On second thought, any memory allocation would almost certainly lead
to a segfault in practice. That just leaves pass-by-value types as
space for the bug to hide.

--
Peter Geoghegan