segfault with select ST_Node(ST_GeomFromText('LINESTRING EMPTY'))

[Cactusbone]

Using PostGIS docker image 14-3.2-alpine, which ships with postgis 3.2.1 and geos 3.10,

I have a segfault with select ST_Node(ST_GeomFromText('LINESTRING EMPTY'))

here's the core dump backtrace

#0  0x00007f36bc780cc7 in geos::noding::SegmentNodeList::add(geos::geom::Coordinate const&, unsigned long) () from /usr/lib/libgeos.so.3.10.2
#1  0x00007f36bc780dea in geos::noding::SegmentNodeList::addEndpoints() () from /usr/lib/libgeos.so.3.10.2
#2  0x00007f36bc781539 in geos::noding::SegmentNodeList::addSplitEdges(std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> >&) () from /usr/lib/libgeos.so.3.10.2
#3  0x00007f36bc77c5c4 in geos::noding::NodedSegmentString::getNodedSubstrings(std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> > const&, std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> >*) () from /usr/lib/libgeos.so.3.10.2
#4  0x00007f36bc77c661 in geos::noding::NodedSegmentString::getNodedSubstrings(std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> > const&) () from /usr/lib/libgeos.so.3.10.2
#5  0x00007f36bc778f1c in geos::noding::IteratedNoder::node(std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> >*, int&, geos::geom::Coordinate&) () from /usr/lib/libgeos.so.3.10.2
#6  0x00007f36bc77900c in geos::noding::IteratedNoder::computeNodes(std::vector<geos::noding::SegmentString*, std::allocator<geos::noding::SegmentString*> >*) () from /usr/lib/libgeos.so.3.10.2
#7  0x00007f36bc777f27 in geos::noding::GeometryNoder::getNoded() () from /usr/lib/libgeos.so.3.10.2
#8  0x00007f36bc778030 in geos::noding::GeometryNoder::node(geos::geom::Geometry const&) () from /usr/lib/libgeos.so.3.10.2
#9  0x00007f36bcd811d7 in GEOSNode_r () from /usr/lib/libgeos_c.so.1
#10 0x00007f36bcc632d0 in lwgeom_node (lwgeom_in=lwgeom_in@entry=0x7f36bcdfbbd8) at lwgeom_geos_node.c:156
#11 0x00007f36bcb6e9bc in ST_Node (fcinfo=0x7f36bcdb8d38) at lwgeom_geos.c:3331
#12 0x000056163af61227 in ExecInterpExpr ()
#13 0x000056163b024c30 in evaluate_expr ()
#14 0x000056163b024e81 in simplify_function ()
#15 0x000056163b025d40 in eval_const_expressions_mutator ()
#16 0x000056163afcc229 in expression_tree_mutator ()
#17 0x000056163afcc4ae in expression_tree_mutator ()
#18 0x000056163b026d5f in eval_const_expressions ()
#19 0x000056163b00e0b8 in preprocess_expression ()
#20 0x000056163b0149a3 in subquery_planner ()
#21 0x000056163b015383 in standard_planner ()
#22 0x000056163b0cfceb in pg_plan_query ()
#23 0x000056163b0cfdd1 in pg_plan_queries ()
#24 0x000056163b0d00a5 in exec_simple_query ()
#25 0x000056163b0d2035 in PostgresMain ()
#26 0x000056163b053f73 in ServerLoop ()
#27 0x000056163b054de1 in PostmasterMain ()
#28 0x000056163addcbce in main ()

I'm not sure if the bug is in geos OR PostGIS, so I'm opening it in both places :)
See https://trac.osgeo.org/postgis/ticket/5145

to reproduce easily:

• start docker container docker run --rm --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgis/postgis:14-3.2-alpine (remove -d to not start in background)
• run query using another container docker run -it --rm --link some-postgres postgres psql postgresql://postgres:mysecretpassword@some-postgres -c "select ST_Node(ST_GeomFromText('LINESTRING EMPTY'))"

2022-05-04 12:16:36.761 UTC [1] LOG: server process (PID 63) was terminated by signal 11: Segmentation fault
2022-05-04 12:16:36.761 UTC [1] DETAIL: Failed process was running: select ST_Node(ST_GeomFromText('LINESTRING EMPTY'))

[Cactusbone]

I think before the fix to #539 it was triggering an assert (in geos 3.9)

Using geos 3.9:
docker run --rm --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgis/postgis:14-3.2 (version shipped with debian bullseye includes geos 3.9)

postgres: postgres postgres 172.17.0.3(50986) SELECT: MonotoneChainBuilder.cpp:76: static std::size_t geos::index::chain::MonotoneChainBuilder::findChainEnd(const geos::geom::CoordinateSequence&, std::size_t): Assertion `start < npts' failed.

I also get the same assert using postgis/postgis:12-2.5 which ships with geos 3.7.1 (from select postgis_full_version())

[pramsey]

This enjoyably crashes for me too, I think I'm on the head of geos. Anyways, nice clear reproducer.

[pramsey]

Fixed at 49c84d5.