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Software: Fix out of bounds accesses in CopyRegion

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Fixes issue 11393.

The problem is that left and top make no sense for a width by height array; they only make sense in a larger array where from which a smaller part is extracted.  Thus, the overall size of the array is provided to CopyRegion in addition to the sub-region.  EncodeXFB already handles the extraction, so CopyRegion's only use there is to resize the image (and thus no sub-region is provided).
This commit is contained in:
Pokechu22
2020-12-11 23:04:32 -08:00
parent 089250fde6
commit 058c7db80b
3 changed files with 43 additions and 32 deletions
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46
Source/Core/VideoBackends/Software/CopyRegion.h
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@ -1,33 +1,53 @@
#pragma once
#include "Common/Assert.h"
#include "Common/MathUtil.h"
#include <cmath>
namespace SW
{
// Modified from
// http://tech-algorithm.com/articles/nearest-neighbor-image-scaling/
// Copies a region of source to a region of destination, performing nearest-neighbor rescaling
template <typename T>
void CopyRegion(const T* const source, const MathUtil::Rectangle<int>& srcrect, T* destination,
const MathUtil::Rectangle<int>& dstrect)
void CopyRegion(const T* const source, const MathUtil::Rectangle<int>& srcrect, const int src_width,
const int src_height, T* destination, const MathUtil::Rectangle<int>& dstrect,
const int dst_width, const int dst_height)
{
ASSERT(srcrect.top >= 0 && srcrect.bottom <= src_height);
ASSERT(srcrect.left >= 0 && srcrect.right <= src_width);
ASSERT(dstrect.top >= 0 && dstrect.bottom <= dst_height);
ASSERT(dstrect.left >= 0 && dstrect.right <= dst_width);
int copy_width = dstrect.GetWidth();
int copy_height = dstrect.GetHeight();
double x_ratio = srcrect.GetWidth() / static_cast<double>(dstrect.GetWidth());
double y_ratio = srcrect.GetHeight() / static_cast<double>(dstrect.GetHeight());
for (int i = 0; i < dstrect.GetHeight(); i++)
for (int y_off = 0; y_off < copy_height; y_off++)
{
for (int j = 0; j < dstrect.GetWidth(); j++)
for (int x_off = 0; x_off < copy_width; x_off++)
{
int destination_x = j + dstrect.left;
int destination_y = i + dstrect.top;
int destination_offset = (destination_y * dstrect.GetWidth()) + destination_x;
int dst_x = dstrect.left + x_off;
int dst_y = dstrect.top + y_off;
int dst_offset = (dst_y * dst_width) + dst_x;
double src_x = std::round(destination_x * x_ratio) + srcrect.left;
double src_y = std::round(destination_y * y_ratio) + srcrect.top;
int src_offset = static_cast<int>((src_y * srcrect.GetWidth()) + src_x);
int src_x = srcrect.left + static_cast<int>(std::round(x_off * x_ratio));
int src_y = srcrect.top + static_cast<int>(std::round(y_off * y_ratio));
int src_offset = (src_y * src_width) + src_x;
destination[destination_offset] = source[src_offset];
destination[dst_offset] = source[src_offset];
}
}
}
// Copies the entire image from source to destination, performing nearest-neighbor rescaling
template <typename T>
void CopyRegion(const T* const source, const int src_width, const int src_height, T* destination,
const int dst_width, const int dst_height)
{
MathUtil::Rectangle<int> srcrect{0, 0, src_width, src_height};
MathUtil::Rectangle<int> dstrect{0, 0, dst_width, dst_height};
CopyRegion(source, srcrect, src_width, src_height, destination, dstrect, dst_width, dst_height);
}
} // namespace SW