[postgis-users] Infinite loop in st_intersects - because of incorrect data out of st_transform?

Mark Cave-Ayland mark.cave-ayland at siriusit.co.uk
Wed Mar 9 07:46:45 PST 2011

On 08/03/11 09:16, Magnus Hagander wrote:

> Since nobody appears to be too interested in producing a quick fix in
> geos, attached is a patch that puts in an *ugly* workaround in
> PostGIS, that simply rejects the infinite values higher up in the
> stack. I don't consider this a long-term fix, but it at least causes
> an error instead of getting stuck in an infinite loop that can only be
> terminated with kill -9... So pending a solution in geos, I would
> suggest this workaround (or something better located written by
> someone who actually know the postgis code better than me) be put in.
> The way it is now, any application that allows the user to specify
> input that could generate such a geometry could trivially
> denial-of-service any postgis site...

Hi Magnus,

What was the discussion with the GEOS people like? Did they consider 
this to be a bug in GEOS or a bug in PostGIS?

The basic workaround looks good, but I'd still be interested on Frank's 
thoughts re: whether infinity is a valid projection output point in 
order to determine the best place for the check.



Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs

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