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Fix known cases of integer overflow

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This commit is contained in:
Erica Fischer
2023-09-07 16:36:28 -07:00
parent 1ccbb6306c
commit ba6bc08de6
4 changed files with 69 additions and 23 deletions
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geometry.cpp
+57 -17
View File
@@ -318,11 +318,14 @@ static void decode_clipped(mapbox::geometry::multi_polygon<long long> &t, drawve
}
}
drawvec clean_or_clip_poly(drawvec &geom, int z, int buffer, bool clip) {
drawvec clean_or_clip_poly(drawvec &geom, int z, int buffer, bool clip, bool try_scaling) {
geom = remove_noop(geom, VT_POLYGON, 0);
mapbox::geometry::multi_polygon<long long> result;
double scale = 16.0;
if (!try_scaling) {
scale = 1.0;
}
bool again = true;
while (again) {
@@ -1023,18 +1026,45 @@ static long long square_distance_from_line_fp(long long point_x, long long point
long long dy = y - point_y;
long long out = dx * dx + dy * dy;
printf("%lld,%lld %f %f %lld,%lld %lld,%lld makes %lld (fp)\n", p2x, p2y, something, u, x, y, dx, dy, out);
return out;
}
static long long square_distance_from_line(long long point_x, long long point_y, long long segA_x, long long segA_y, long long segB_x, long long segB_y) {
long long fpversion = square_distance_from_line_fp(point_x, point_y, segA_x, segA_y, segB_x, segB_y);
size_t bits(long long n) {
if (n < 0) {
n = -n;
}
for (size_t i = 0; i < 64; i++) {
if (n <= (1LL << i)) {
return i + 1;
}
}
return 64;
}
static long long square_distance_from_line(long long point_x, long long point_y, long long segA_x, long long segA_y, long long segB_x, long long segB_y, long long divisor) {
// long long fpversion = square_distance_from_line_fp(point_x, point_y, segA_x, segA_y, segB_x, segB_y);
if (divisor != 1) {
point_x /= divisor;
point_y /= divisor;
segA_x /= divisor;
segA_y /= divisor;
segB_x /= divisor;
segB_y /= divisor;
}
const long long scale = 1024;
long long p2x = segB_x - segA_x;
long long p2y = segB_y - segA_y;
// printf("%lld %zu %lld %zu %lld %zu %lld %zu\n", p2x, bits(p2x), (point_x - segA_x), bits(point_x - segA_x), p2y, bits(p2y), (point_y - segA_y), bits(point_y - segA_y));
if (bits(p2x) + bits(point_x - segA_x) > 63 || bits(p2y) + bits(point_y - segA_y) > 63) {
printf("overflow with divisor %lld\n", divisor);
}
long long something = p2x * p2x + p2y * p2y;
double u = 0 == something ? 0 : ((point_x - segA_x) * p2x + (point_y - segA_y) * p2y) / (something / scale);
double u = 0 == (something / scale) ? 0 : ((point_x - segA_x) * p2x + (point_y - segA_y) * p2y) / (something / scale);
if (u > scale) {
u = scale;
@@ -1049,7 +1079,9 @@ static long long square_distance_from_line(long long point_x, long long point_y,
long long dy = y - point_y;
long long out = dx * dx + dy * dy;
out *= divisor;
#if 0
printf("%lld,%lld %lld %f %lld,%lld %lld,%lld makes %lld\n", p2x, p2y, something, u, x, y, dx, dy, out);
if (fpversion > out) {
printf("%.3f ", (double) fpversion / out);
@@ -1057,15 +1089,16 @@ static long long square_distance_from_line(long long point_x, long long point_y,
printf("%.3f ", (double) out / fpversion);
}
printf("for %lld,%lld in %lld,%lld to %lld,%lld: fp %lld vs quant %lld\n", point_x, point_y, segA_x, segA_y, segB_x, segB_y, fpversion, out);
#endif
return out;
}
// https://github.com/Project-OSRM/osrm-backend/blob/733d1384a40f/Algorithms/DouglasePeucker.cpp
static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t kept, size_t retain) {
static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t kept, size_t retain, long long scale) {
e = e * e;
std::stack<int> recursion_stack;
printf("doug of %d\n", n);
// printf("doug of %d\n", n);
if (!geom[start + 0].necessary || !geom[start + n - 1].necessary) {
fprintf(stderr, "endpoints not marked necessary\n");
@@ -1088,7 +1121,7 @@ static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t ke
int first = recursion_stack.top();
recursion_stack.pop();
printf("sub-doug of %d\n", second - first + 1);
// printf("sub-doug of %d\n", second - first + 1);
long long max_distance = -1;
int farthest_element_index;
@@ -1102,7 +1135,7 @@ static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t ke
int i;
if (geom[start + first] < geom[start + second]) {
for (i = first + 1; i < second; i++) {
long long temp_dist = square_distance_from_line(geom[start + i].x, geom[start + i].y, geom[start + first].x, geom[start + first].y, geom[start + second].x, geom[start + second].y);
long long temp_dist = square_distance_from_line(geom[start + i].x, geom[start + i].y, geom[start + first].x, geom[start + first].y, geom[start + second].x, geom[start + second].y, scale);
long long distance = std::llabs(temp_dist);
@@ -1113,7 +1146,7 @@ static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t ke
}
} else {
for (i = second - 1; i > first; i--) {
long long temp_dist = square_distance_from_line(geom[start + i].x, geom[start + i].y, geom[start + first].x, geom[start + first].y, geom[start + second].x, geom[start + second].y);
long long temp_dist = square_distance_from_line(geom[start + i].x, geom[start + i].y, geom[start + first].x, geom[start + first].y, geom[start + second].x, geom[start + second].y, scale);
long long distance = std::llabs(temp_dist);
@@ -1133,13 +1166,13 @@ static void douglas_peucker(drawvec &geom, int start, int n, double e, size_t ke
recursion_stack.push(first);
recursion_stack.push(farthest_element_index);
printf("split1: %d to %d, %d\n", first, farthest_element_index, farthest_element_index - first + 1);
// printf("split1: %d to %d, %d\n", first, farthest_element_index, farthest_element_index - first + 1);
}
if (1 < second - farthest_element_index) {
recursion_stack.push(farthest_element_index);
recursion_stack.push(second);
printf("split2: %d to %d, %d\n", farthest_element_index, second, second - farthest_element_index + 1);
// printf("split2: %d to %d, %d\n", farthest_element_index, second, second - farthest_element_index + 1);
}
}
}
@@ -1234,7 +1267,11 @@ drawvec simplify_lines(drawvec &geom, int z, int detail, bool mark_tile_bounds,
if (additional[A_VISVALINGAM]) {
visvalingam(geom, i, j, scale, retain);
} else {
douglas_peucker(geom, i, j - i, res * simplification, 2, retain);
long long divisor = 1;
if (z < 18) {
divisor = 1LL << (18 - z);
}
douglas_peucker(geom, i, j - i, res * simplification, 2, retain, divisor);
}
}
i = j - 1;
@@ -1377,8 +1414,9 @@ drawvec fix_polygon(drawvec &geom) {
long long dist2 = 0;
long long furthest = 0;
for (size_t a = 0; a + 1 < ring.size(); a++) {
long long xd = ring[a].x - xtotal;
long long yd = ring[a].y - ytotal;
// division by 16 because these are z0 coordinates and we need to avoid overflow
long long xd = (ring[a].x - xtotal) / 16;
long long yd = (ring[a].y - ytotal) / 16;
long long d2 = xd * xd + yd * yd;
if (d2 > dist2 || (d2 == dist2 && ring[a] < ring[furthest])) {
dist2 = d2;
@@ -1390,8 +1428,9 @@ drawvec fix_polygon(drawvec &geom) {
long long dist2b = 0;
long long furthestb = 0;
for (size_t a = 0; a + 1 < ring.size(); a++) {
long long xd = ring[a].x - ring[furthest].x;
long long yd = ring[a].y - ring[furthest].y;
// division by 16 because these are z0 coordinates and we need to avoid overflow
long long xd = (ring[a].x - ring[furthest].x) / 16;
long long yd = (ring[a].y - ring[furthest].y) / 16;
long long d2 = xd * xd + yd * yd;
if (d2 > dist2b || (d2 == dist2b && ring[a] < ring[furthestb])) {
dist2b = d2;
@@ -1804,7 +1843,8 @@ double label_goodness(const drawvec &dv, long long x, long long y) {
}
if (i > 0 && dv[i].op == VT_LINETO) {
squared = square_distance_from_line(x, y, dv[i - 1].x, dv[i - 1].y, dv[i].x, dv[i].y);
// division by 16 to avoid overflow with z0 coordinates
squared = square_distance_from_line(x, y, dv[i - 1].x, dv[i - 1].y, dv[i].x, dv[i].y, 16);
if (squared < closest) {
closest = squared;
}
geometry.hpp
+1 -1
View File
@@ -65,7 +65,7 @@ void to_tile_scale(drawvec &geom, int z, int detail);
drawvec from_tile_scale(drawvec const &geom, int z, int detail);
drawvec remove_noop(drawvec geom, int type, int shift);
drawvec clip_point(drawvec &geom, int z, long long buffer);
drawvec clean_or_clip_poly(drawvec &geom, int z, int buffer, bool clip);
drawvec clean_or_clip_poly(drawvec &geom, int z, int buffer, bool clip, bool try_scaling);
drawvec simple_clip_poly(drawvec &geom, int z, int buffer, drawvec &shared_nodes);
drawvec close_poly(drawvec &geom);
drawvec reduce_tiny_poly(drawvec &geom, int z, int detail, bool *still_needs_simplification, bool *reduced_away, double *accum_area, serial_feature *this_feature, serial_feature *tiny_feature);
plugin.cpp
+2 -1
View File
@@ -202,7 +202,8 @@ std::vector<mvt_layer> parse_layers(int fd, int z, unsigned x, unsigned y, std::
}
if (mb_geometry[t] == VT_POLYGON) {
dv = clean_or_clip_poly(dv, 0, 0, false);
// we can try scaling up because these are tile coordinates
dv = clean_or_clip_poly(dv, 0, 0, false, true);
if (dv.size() < 3) {
dv.clear();
}
tile.cpp
+9 -4
View File
@@ -573,7 +573,9 @@ double simplify_partial(partial *p, drawvec &shared_nodes) {
// clean coalesced polygons before simplification to avoid
// introducing shards between shapes that otherwise would have
// unioned exactly
geom = clean_or_clip_poly(geom, 0, 0, false);
//
// don't try to scale up because these are still world coordinates
geom = clean_or_clip_poly(geom, 0, 0, false, false);
}
// continues to simplify to line_detail even if we have extra detail
@@ -614,7 +616,8 @@ void *partial_feature_worker(void *v) {
// Give Clipper a chance to try to fix it.
{
drawvec before = geom;
geom = clean_or_clip_poly(geom, 0, 0, false);
// we can try scaling up because this is now tile scale
geom = clean_or_clip_poly(geom, 0, 0, false, true);
if (additional[A_DEBUG_POLYGON]) {
check_polygon(geom);
}
@@ -2396,7 +2399,8 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
for (auto &g : partials[simplified_geometry_through].geoms) {
if (partials[simplified_geometry_through].t == VT_POLYGON) {
g = clean_or_clip_poly(g, 0, 0, false);
// don't scale up because this is still world coordinates
g = clean_or_clip_poly(g, 0, 0, false, false);
}
}
}
@@ -2668,7 +2672,8 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
if (layer_features[x].type == VT_POLYGON) {
if (layer_features[x].coalesced) {
layer_features[x].geom = clean_or_clip_poly(layer_features[x].geom, 0, 0, false);
// we can try scaling up because this is tile coordinates
layer_features[x].geom = clean_or_clip_poly(layer_features[x].geom, 0, 0, false, true);
}
layer_features[x].geom = close_poly(layer_features[x].geom);