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authorLei Zhang <thestig@chromium.org>2017-12-05 20:26:33 +0000
committerChromium commit bot <commit-bot@chromium.org>2017-12-05 20:26:33 +0000
commit099fc90d25059f19919471301f459949c566846f (patch)
tree581ffe03269c3192d1f8f55a803562bc96221d50 /core/fxge/dib
parent12ec6760afd92b63d185854008a55762fe39f866 (diff)
downloadpdfium-099fc90d25059f19919471301f459949c566846f.tar.xz
Avoid integer overflows in CPDF_FixedMatrix::Transform().
Use floating point math and saturated_cast to calculate the transform. Refactor CFX_BilinearMatrix::Transform() to share common code, instead of using integer math and CheckedNumerics. BUG=chromium:791048 Change-Id: Ib3812b3b3b9373a8eb3b1dde12cb28d424e0bb3e Reviewed-on: https://pdfium-review.googlesource.com/20390 Reviewed-by: Tom Sepez <tsepez@chromium.org> Reviewed-by: dsinclair <dsinclair@chromium.org> Commit-Queue: Lei Zhang <thestig@chromium.org>
Diffstat (limited to 'core/fxge/dib')
-rw-r--r--core/fxge/dib/cfx_imagetransformer.cpp36
1 files changed, 15 insertions, 21 deletions
diff --git a/core/fxge/dib/cfx_imagetransformer.cpp b/core/fxge/dib/cfx_imagetransformer.cpp
index 1904c3a0d6..565d38b2e2 100644
--- a/core/fxge/dib/cfx_imagetransformer.cpp
+++ b/core/fxge/dib/cfx_imagetransformer.cpp
@@ -6,11 +6,13 @@
#include "core/fxge/dib/cfx_imagetransformer.h"
+#include <cmath>
#include <memory>
#include <utility>
#include "core/fxge/dib/cfx_imagestretcher.h"
#include "core/fxge/fx_dib.h"
+#include "third_party/base/numerics/safe_conversions.h"
#include "third_party/base/ptr_util.h"
namespace {
@@ -164,11 +166,17 @@ class CPDF_FixedMatrix {
f(FXSYS_round(src.f * kBase)) {}
void Transform(int x, int y, int* x1, int* y1) const {
- *x1 = (a * x + c * y + e + kBase / 2) / kBase;
- *y1 = (b * x + d * y + f + kBase / 2) / kBase;
+ std::pair<float, float> val = TransformInternal(x, y);
+ *x1 = pdfium::base::saturated_cast<int>(val.first / kBase);
+ *y1 = pdfium::base::saturated_cast<int>(val.second / kBase);
}
protected:
+ std::pair<float, float> TransformInternal(float x, float y) const {
+ return std::make_pair(a * x + c * y + e + kBase / 2,
+ b * x + d * y + f + kBase / 2);
+ }
+
const int a;
const int b;
const int c;
@@ -182,30 +190,16 @@ class CFX_BilinearMatrix : public CPDF_FixedMatrix {
explicit CFX_BilinearMatrix(const CFX_Matrix& src) : CPDF_FixedMatrix(src) {}
void Transform(int x, int y, int* x1, int* y1, int* res_x, int* res_y) const {
- pdfium::base::CheckedNumeric<int> val = a;
- pdfium::base::CheckedNumeric<int> val2 = c;
- val *= x;
- val2 *= y;
- val += val2 + e + (kBase / 2);
- *x1 = val.ValueOrDefault(0);
-
- val = b;
- val2 = d;
- val *= x;
- val2 *= y;
- val += val2 + f + (kBase / 2);
- *y1 = val.ValueOrDefault(0);
-
- *res_x = *x1 % kBase;
- *res_y = *y1 % kBase;
+ std::pair<float, float> val = TransformInternal(x, y);
+ *x1 = pdfium::base::saturated_cast<int>(val.first / kBase);
+ *y1 = pdfium::base::saturated_cast<int>(val.second / kBase);
+ *res_x = static_cast<int>(fmodf(val.first, kBase));
+ *res_y = static_cast<int>(fmodf(val.second, kBase));
if (*res_x < 0 && *res_x > -kBase)
*res_x = kBase + *res_x;
if (*res_y < 0 && *res_x > -kBase)
*res_y = kBase + *res_y;
-
- *x1 /= kBase;
- *y1 /= kBase;
}
};