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diff --git a/third_party/agg23/agg_rasterizer_scanline_aa.cpp b/third_party/agg23/agg_rasterizer_scanline_aa.cpp
index 1fe9a0c32..9254d830d 100644
--- a/third_party/agg23/agg_rasterizer_scanline_aa.cpp
+++ b/third_party/agg23/agg_rasterizer_scanline_aa.cpp
@@ -502,4 +502,16 @@ int rasterizer_scanline_aa::calculate_area(int cover, int shift)
result <<= shift;
return result;
}
+// static
+bool rasterizer_scanline_aa::safe_add(int* op1, int op2)
+{
+ pdfium::base::CheckedNumeric<int> safeOp1 = *op1;
+ safeOp1 += op2;
+ if(!safeOp1.IsValid()) {
+ return false;
+ }
+
+ *op1 = safeOp1.ValueOrDie();
+ return true;
+}
}
diff --git a/third_party/agg23/agg_rasterizer_scanline_aa.h b/third_party/agg23/agg_rasterizer_scanline_aa.h
index 281933710..eade78333 100644
--- a/third_party/agg23/agg_rasterizer_scanline_aa.h
+++ b/third_party/agg23/agg_rasterizer_scanline_aa.h
@@ -338,14 +338,33 @@ public:
const cell_aa* cur_cell = *cells;
int x = cur_cell->x;
int area = cur_cell->area;
- cover += cur_cell->cover;
+ bool seen_area_overflow = false;
+ bool seen_cover_overflow = false;
+ if(!safe_add(&cover, cur_cell->cover)) {
+ break;
+ }
while(--num_cells) {
cur_cell = *++cells;
if(cur_cell->x != x) {
break;
}
- area += cur_cell->area;
- cover += cur_cell->cover;
+ if(seen_area_overflow) {
+ continue;
+ }
+ if(!safe_add(&area, cur_cell->area)) {
+ seen_area_overflow = true;
+ continue;
+ }
+ if(!safe_add(&cover, cur_cell->cover)) {
+ seen_cover_overflow = true;
+ break;
+ }
+ }
+ if(seen_area_overflow) {
+ continue;
+ }
+ if(seen_cover_overflow) {
+ break;
}
if(area) {
unsigned alpha = calculate_alpha(calculate_area(cover, poly_base_shift + 1) - area, no_smooth);
@@ -459,6 +478,7 @@ private:
}
private:
static int calculate_area(int cover, int shift);
+ static bool safe_add(int* op1, int op2);
outline_aa m_outline;
filling_rule_e m_filling_rule;