Fix out of bounds access in dtMergeCorridorStartMoved and add tests (r…

…ecastnavigation#635)

size can become negative if req > maxPath. This may happen when visited buffer is larger than path buffer.

Add tests to cover different use cases of the function including Should add visited points not present in path up to the path capacity to cover the fix.

List tests files explicitly. When new file is added CMake does not add it to the already generated list if GLOB is used.

DetourCrowd/Source/DetourPathCorridor.cpp

@@ -59,13 +59,13 @@ int dtMergeCorridorStartMoved(dtPolyRef* path, const int npath, const int maxPat
 	int size = dtMax(0, npath-orig);
 	if (req+size > maxPath)
 		size = maxPath-req;
-	if (size)
+	if (size > 0)
 		memmove(path+req, path+orig, size*sizeof(dtPolyRef));
-	
+
 	// Store visited
-	for (int i = 0; i < req; ++i)
-		path[i] = visited[(nvisited-1)-i];				
-	
+	for (int i = 0, n = dtMin(req, maxPath); i < n; ++i)
+		path[i] = visited[(nvisited-1)-i];
+
 	return req+size;
 }
 

RecastDemo/premake5.lua

@@ -223,14 +223,15 @@ project "Tests"
 		"../Tests/Recast/*.cpp",
 		"../Tests/Detour/*.h",
 		"../Tests/Detour/*.cpp",
+		"../Tests/DetourCrowd/*.cpp",
 		"../Tests/Contrib/catch2/*.cpp"
 	}
 
 	-- project dependencies
 	links { 
 		"DebugUtils",
-		"Detour",
 		"DetourCrowd",
+		"Detour",
 		"DetourTileCache",
 		"Recast",
 	}

Tests/CMakeLists.txt

@@ -1,14 +1,19 @@
-file(GLOB TESTS_SOURCES Detour/*.cpp Recast/*.cpp)
-
 include_directories(../Detour/Include)
 include_directories(../Recast/Include)
 
-add_executable(Tests ${TESTS_SOURCES})
+add_executable(Tests
+	Detour/Tests_Detour.cpp
+	Recast/Bench_rcVector.cpp
+	Recast/Tests_Alloc.cpp
+	Recast/Tests_Recast.cpp
+	Recast/Tests_RecastFilter.cpp
+	DetourCrowd/Tests_DetourPathCorridor.cpp
+)
 
 set_property(TARGET Tests PROPERTY CXX_STANDARD 17)
 
-add_dependencies(Tests Recast Detour)
-target_link_libraries(Tests Recast Detour)
+add_dependencies(Tests Recast Detour DetourCrowd)
+target_link_libraries(Tests Recast Detour DetourCrowd)
 
 find_package(Catch2 QUIET)
 if (Catch2_FOUND)

Tests/DetourCrowd/Tests_DetourPathCorridor.cpp

@@ -0,0 +1,119 @@
+#include "catch2/catch_all.hpp"
+
+#include "DetourPathCorridor.h"
+
+TEST_CASE("dtMergeCorridorStartMoved")
+{
+    SECTION("Should handle empty input")
+    {
+        dtPolyRef* const path = nullptr;
+        const int npath = 0;
+        const int maxPath = 0;
+        const dtPolyRef* const visited = nullptr;
+        const int nvisited = 0;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 0);
+    }
+
+    SECTION("Should handle empty visited")
+    {
+        dtPolyRef path[] = {1};
+        const int npath = 1;
+        const int maxPath = 1;
+        const dtPolyRef* const visited = nullptr;
+        const int nvisited = 0;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 1);
+        const dtPolyRef expectedPath[] = {1};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should handle empty path")
+    {
+        dtPolyRef* const path = nullptr;
+        const int npath = 0;
+        const int maxPath = 0;
+        const dtPolyRef visited[] = {1};
+        const int nvisited = 1;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 0);
+    }
+
+    SECTION("Should strip visited points from path except last")
+    {
+        dtPolyRef path[] = {1, 2};
+        const int npath = 2;
+        const int maxPath = 2;
+        const dtPolyRef visited[] = {1, 2};
+        const int nvisited = 2;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 1);
+        const dtPolyRef expectedPath[] = {2, 2};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should add visited points not present in path in reverse order")
+    {
+        dtPolyRef path[] = {1, 2, 0};
+        const int npath = 2;
+        const int maxPath = 3;
+        const dtPolyRef visited[] = {1, 2, 3, 4};
+        const int nvisited = 4;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 3);
+        const dtPolyRef expectedPath[] = {4, 3, 2};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should add visited points not present in path up to the path capacity")
+    {
+        dtPolyRef path[] = {1, 2, 0};
+        const int npath = 2;
+        const int maxPath = 3;
+        const dtPolyRef visited[] = {1, 2, 3, 4, 5};
+        const int nvisited = 5;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 3);
+        const dtPolyRef expectedPath[] = {5, 4, 3};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should not change path if there is no intersection with visited")
+    {
+        dtPolyRef path[] = {1, 2};
+        const int npath = 2;
+        const int maxPath = 2;
+        const dtPolyRef visited[] = {3, 4};
+        const int nvisited = 2;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 2);
+        const dtPolyRef expectedPath[] = {1, 2};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should save unvisited path points")
+    {
+        dtPolyRef path[] = {1, 2, 0};
+        const int npath = 2;
+        const int maxPath = 3;
+        const dtPolyRef visited[] = {1, 3};
+        const int nvisited = 2;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 3);
+        const dtPolyRef expectedPath[] = {3, 1, 2};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+
+    SECTION("Should save unvisited path points up to the path capacity")
+    {
+        dtPolyRef path[] = {1, 2};
+        const int npath = 2;
+        const int maxPath = 2;
+        const dtPolyRef visited[] = {1, 3};
+        const int nvisited = 2;
+        const int result = dtMergeCorridorStartMoved(path, npath, maxPath, visited, nvisited);
+        CHECK(result == 2);
+        const dtPolyRef expectedPath[] = {3, 1};
+        CHECK_THAT(path, Catch::Matchers::RangeEquals(expectedPath));
+    }
+}