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Merged
sfreilich merged 1 commit into from
Apr 24, 2025
Merged

Fail if coords are outside of a safe range #71

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8 changes: 8 additions & 0 deletions Include/tesselator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,14 @@ typedef struct TESSalloc TESSalloc;

#define TESS_NOTUSED(v) do { (void)(1 ? (void)0 : ( (void)(v) ) ); } while(0)

// These two constants define the valid input coordinate range the library is
// able to operate on. Tesselation will fail if any of the coordinates are not
// within this range. Clients are responsible for dealing with inputs outside of
// this range (e.g. clamping or filtering invalid points, scaling down the
// coordinate space).
#define TESS_MAX_VALID_INPUT_VALUE ((TESSreal) (1<<23))
#define TESS_MIN_VALID_INPUT_VALUE (-TESS_MAX_VALID_INPUT_VALUE)

// Custom memory allocator interface.
// The internal memory allocator allocates mesh edges, vertices and faces
// as well as dictionary nodes and active regions in buckets and uses simple
Expand Down
9 changes: 8 additions & 1 deletion Source/tess.c
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Expand Up @@ -918,6 +918,11 @@ void OutputContours( TESStesselator *tess, TESSmesh *mesh, int vertexSize )
}
}

int IsValidCoord(TESSreal coord) {
return coord <= TESS_MAX_VALID_INPUT_VALUE &&
coord >= TESS_MIN_VALID_INPUT_VALUE;
}

void tessAddContour( TESStesselator *tess, int size, const void* vertices,
int stride, int numVertices )
{
Expand All @@ -942,7 +947,9 @@ void tessAddContour( TESStesselator *tess, int size, const void* vertices,
{
const TESSreal* coords = (const TESSreal*)src;
src += stride;
if (isnan(coords[0]) || isnan(coords[1]) || (size > 2 && isnan(coords[2]))) {
if (!IsValidCoord(coords[0]) ||
!IsValidCoord(coords[1]) ||
(size > 2 && !IsValidCoord(coords[2]))) {
// "Out of memory" isn't quite right, but give up and bail out
tess->outOfMemory = 1;
return;
Expand Down
52 changes: 39 additions & 13 deletions Tests/libtess2_test.cc
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Expand Up @@ -167,10 +167,9 @@ TEST_F(Libtess2Test, FloatOverflowQuad) {
{kFloatMin, kFloatMax},
{kFloatMax, kFloatMax},
{kFloatMax, kFloatMin}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 2);
}

TEST_F(Libtess2Test, SingularityQuad) {
Expand All @@ -188,34 +187,30 @@ TEST_F(Libtess2Test, DegenerateQuad) {
{0.64113313f, -1.f},
{-0.f, -0.f},
{-3.40282347e+38f, 1.f}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 2);
}

TEST_F(Libtess2Test, WidthOverflowsTri) {
AddPolyline(tess, {{-2e+38f, 0}, {0, 0}, {2e+38f, -1}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 1);
}

TEST_F(Libtess2Test, HeightOverflowsTri) {
AddPolyline(tess, {{0, 0}, {0, 2e+38f}, {-1, -2e+38f}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 1);
}

TEST_F(Libtess2Test, AreaOverflowsTri) {
AddPolyline(tess, {{-2e+37f, 0.f}, {0, 5}, {1e37f, -5}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 1);
}

TEST_F(Libtess2Test, NanQuad) {
Expand All @@ -229,7 +224,7 @@ TEST_F(Libtess2Test, NanQuad) {
EXPECT_EQ(tessGetElementCount(tess), 0);
}

TEST_F(Libtess2Test, DegenerateSquiggle) {
TEST_F(Libtess2Test, AvoidsCrashWhileFindingIntersection) {
// Previously, this failed an assert while finding an intersection because
// that fell back to taking a midpoint between two coordinates in a way that
// could get the wrong answer because of the sum overflowing max float.
Expand Down Expand Up @@ -261,10 +256,41 @@ TEST_F(Libtess2Test, DegenerateSquiggle) {
{-1.f, 3.40282347e+38f},
{-0.f, 0.34419331f},
{1.f, 1.f}});
EXPECT_NE(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
}

TEST_F(Libtess2Test, AvoidsCrashInAddRightEdges) {
AddPolyline(tess, {{{-0.5f, 1.f},
{3.40282347e+38f, 0.f},
{0.349171013f, 1.f},
{1.f, 0.f},
{1.f, -0.f},
{0.594775498f, -0.f},
{0.f, -0.f},
{-0.f, 1.f},
{0.f, 1.f},
{2.20929384f, 1.f},
{1.f, 1.f},
{-0.f, -0.f},
{3.40282347e+38f, -0.f},
{-1.f, 0.f},
{1.70141173e+38f, 0.391036272f},
{3.40282347e+38f, 0.371295959f},
{3.40282347e+38f, -0.f},
{0.f, 0.234747186f},
{-1.f, 1.f},
{-1.f, -0.f},
{3.40282347e+38f, 1.f},
{-0.f, -0.f},
{3.40282347e+38f, 1.f},
{0.434241712f, 0.f},
{1.f, 0.211511821f},
{3.40282347e+38f, 1.f}}});
EXPECT_EQ(tessTesselate(tess, TESS_WINDING_POSITIVE, TESS_POLYGONS,
kNumTriangleVertices, kComponentCount, nullptr),
0);
EXPECT_EQ(tessGetElementCount(tess), 13);
}

} // namespace