SERVER-13258 ensure S2 poly loops have 3 points after dedup'ing

2 files changed, 14 insertions, 0 deletions

diff --git a/src/mongo/db/geo/geoparser.cpp b/src/mongo/db/geo/geoparser.cpp
index a4d21ca7a61..e5fe800ea23 100644
--- a/src/mongo/db/geo/geoparser.cpp
+++ b/src/mongo/db/geo/geoparser.cpp
@@ -164,6 +164,8 @@ namespace mongo {
         // The last point is duplicated.  We drop it, since S2Loop expects no
         // duplicate points
         exteriorVertices.resize(exteriorVertices.size() - 1);
+        // S2 Polygon loops must have 3 vertices
+        if (exteriorVertices.size() < 3) { return false; }
 
         S2PolygonBuilderOptions polyOptions;
         polyOptions.set_validate(true);
@@ -185,6 +187,8 @@ namespace mongo {
             eraseDuplicatePoints(&holePoints);
             // Drop the duplicated last point.
             holePoints.resize(holePoints.size() - 1);
+            // S2 Polygon loops must have 3 vertices
+            if (holePoints.size() < 3) { return false; }
             // Interior rings are clockwise.
             S2Loop holeLoop(holePoints);
             holeLoop.Normalize();
diff --git a/src/mongo/db/geo/geoparser_test.cpp b/src/mongo/db/geo/geoparser_test.cpp
index 5f6c4ffd89b..eeac3725336 100644
--- a/src/mongo/db/geo/geoparser_test.cpp
+++ b/src/mongo/db/geo/geoparser_test.cpp
@@ -168,6 +168,16 @@ namespace {
             &polygonD);
         // Also removed in the loop.
         ASSERT_FALSE(polygonD.polygon.Contains(point.point));
+
+        //
+        // Bad polygon examples
+        //
+
+        // Polygon with not enough points, because some are duplicated
+        PolygonWithCRS polygonBad;
+        ASSERT_FALSE(GeoParser::parsePolygon(
+            fromjson("{'type':'Polygon', 'coordinates':[[ [0,0], [0,0], [5,5], [5,5], [0,0] ]]}"),
+            &polygonBad));
     }
 
     TEST(GeoParser, legacyPoint) {