[postgis-tickets] r16869 - Fix undefined behaviour in ptarray_clone_deep

[Raul]

Author: algunenano
Date: 2018-10-02 04:40:51 -0700 (Tue, 02 Oct 2018)
New Revision: 16869

Modified:
   branches/2.4/NEWS
   branches/2.4/liblwgeom/ptarray.c
Log:
Fix undefined behaviour in ptarray_clone_deep

References #4191


Modified: branches/2.4/NEWS
===================================================================
--- branches/2.4/NEWS	2018-10-02 11:40:07 UTC (rev 16868)
+++ branches/2.4/NEWS	2018-10-02 11:40:51 UTC (rev 16869)
@@ -6,6 +6,7 @@
   - #4181, St_AsMVTGeom: Avoid type changes due to validation (Raúl Marín)
   - #4183, St_AsMVTGeom: Drop invalid geometries after simplification (Raúl Marín)
   - #4189, Fix undefined behaviour in SADFWrite (Raúl Marín)
+  - #4191, Fix undefined behaviour in ptarray_clone_deep (Raúl Marín)
 
 
 PostGIS 2.4.5

Modified: branches/2.4/liblwgeom/ptarray.c
===================================================================
--- branches/2.4/liblwgeom/ptarray.c	2018-10-02 11:40:07 UTC (rev 16868)
+++ branches/2.4/liblwgeom/ptarray.c	2018-10-02 11:40:51 UTC (rev 16869)
@@ -630,7 +630,6 @@
 ptarray_clone_deep(const POINTARRAY *in)
 {
 	POINTARRAY *out = lwalloc(sizeof(POINTARRAY));
-	size_t size;
 
 	LWDEBUG(3, "ptarray_clone_deep called.");
 
@@ -640,9 +639,17 @@
 
 	FLAGS_SET_READONLY(out->flags, 0);
 
-	size = in->npoints * ptarray_point_size(in);
-	out->serialized_pointlist = lwalloc(size);
-	memcpy(out->serialized_pointlist, in->serialized_pointlist, size);
+	if (!in->npoints)
+	{
+		// Avoid calling lwalloc of 0 bytes
+		out->serialized_pointlist = NULL;
+	}
+	else
+	{
+		size_t size = in->npoints * ptarray_point_size(in);
+		out->serialized_pointlist = lwalloc(size);
+		memcpy(out->serialized_pointlist, in->serialized_pointlist, size);
+	}
 
 	return out;
 }