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authordsinclair <dsinclair@chromium.org>2016-09-15 12:21:39 -0700
committerCommit bot <commit-bot@chromium.org>2016-09-15 12:21:39 -0700
commit4935e606c632e38af8fca1729f8688fa0d152b90 (patch)
treee24d2ac486c4b5029ed2d02c0328647e01bf8f78 /third_party/agg23/agg_rasterizer_scanline_aa.cpp
parent72177dadac8f9765440b3aa01e2668f60a8b3f43 (diff)
downloadpdfium-4935e606c632e38af8fca1729f8688fa0d152b90.tar.xz
Use safe math when rendering line segments in AGG.
It is possible for the calculations in outline_aa::render_line to overflow as the |p| variable is calculated. This Cl updates the routine to use checked math when calculating the value of |p|. BUG=chromium:647026 Review-Url: https://codereview.chromium.org/2347603002
Diffstat (limited to 'third_party/agg23/agg_rasterizer_scanline_aa.cpp')
-rw-r--r--third_party/agg23/agg_rasterizer_scanline_aa.cpp38
1 files changed, 24 insertions, 14 deletions
diff --git a/third_party/agg23/agg_rasterizer_scanline_aa.cpp b/third_party/agg23/agg_rasterizer_scanline_aa.cpp
index 46379f6dfd..c6b3f013a0 100644
--- a/third_party/agg23/agg_rasterizer_scanline_aa.cpp
+++ b/third_party/agg23/agg_rasterizer_scanline_aa.cpp
@@ -48,6 +48,7 @@
//----------------------------------------------------------------------------
#include <limits.h>
#include "agg_rasterizer_scanline_aa.h"
+#include "third_party/base/numerics/safe_math.h"
namespace agg
{
AGG_INLINE void cell_aa::set_cover(int c, int a)
@@ -237,7 +238,7 @@ void outline_aa::render_line(int x1, int y1, int x2, int y2)
int fy1 = y1 & poly_base_mask;
int fy2 = y2 & poly_base_mask;
int x_from, x_to;
- int p, rem, mod, lift, delta, first, incr;
+ int rem, mod, lift, delta, first, incr;
if(ey1 == ey2) {
render_hline(ey1, x1, fy1, x2, fy2);
return;
@@ -268,16 +269,22 @@ void outline_aa::render_line(int x1, int y1, int x2, int y2)
m_cur_cell.add_cover(delta, two_fx * delta);
return;
}
- p = (poly_base_size - fy1) * dx;
+ pdfium::base::CheckedNumeric<int> safeP = poly_base_size - fy1;
+ safeP *= dx;
+ if (!safeP.IsValid())
+ return;
first = poly_base_size;
if(dy < 0) {
- p = fy1 * dx;
- first = 0;
- incr = -1;
- dy = -dy;
+ safeP = fy1;
+ safeP *= dx;
+ if (!safeP.IsValid())
+ return;
+ first = 0;
+ incr = -1;
+ dy = -dy;
}
- delta = p / dy;
- mod = p % dy;
+ delta = safeP.ValueOrDie() / dy;
+ mod = safeP.ValueOrDie() % dy;
if(mod < 0) {
delta--;
mod += dy;
@@ -287,12 +294,15 @@ void outline_aa::render_line(int x1, int y1, int x2, int y2)
ey1 += incr;
set_cur_cell(x_from >> poly_base_shift, ey1);
if(ey1 != ey2) {
- p = poly_base_size * dx;
- lift = p / dy;
- rem = p % dy;
- if(rem < 0) {
- lift--;
- rem += dy;
+ safeP = static_cast<int>(poly_base_size);
+ safeP *= dx;
+ if (!safeP.IsValid())
+ return;
+ lift = safeP.ValueOrDie() / dy;
+ rem = safeP.ValueOrDie() % dy;
+ if (rem < 0) {
+ lift--;
+ rem += dy;
}
mod -= dy;
while(ey1 != ey2) {