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Fixed overflow in surface pitch calculation

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slouken committed Jun 17, 2020
1 parent efe0935 commit a7ff6e96155f550a5597621ebeddd03c98aa9294
Showing with 15 additions and 8 deletions.
  1. +15 −8 src/video/SDL_surface.c
@@ -28,24 +28,23 @@
#include "SDL_yuv_c.h"


/* Check to make sure we can safely check multiplication of surface w and pitch and it won't overflow size_t */
SDL_COMPILE_TIME_ASSERT(surface_size_assumptions,
sizeof(int) == sizeof(Sint32) && sizeof(size_t) >= sizeof(Sint32));
/* Check to make sure we can safely check multiplication of surface w and pitch and it won't overflow Sint64 */
SDL_COMPILE_TIME_ASSERT(surface_size_assumptions, sizeof(int) == sizeof(Sint32));

/* Public routines */

/*
* Calculate the pad-aligned scanline width of a surface
*/
static int
static Sint64
SDL_CalculatePitch(Uint32 format, int width)
{
int pitch;
Sint64 pitch;

if (SDL_ISPIXELFORMAT_FOURCC(format) || SDL_BITSPERPIXEL(format) >= 8) {
pitch = (width * SDL_BYTESPERPIXEL(format));
pitch = ((Sint64)width * SDL_BYTESPERPIXEL(format));
} else {
pitch = ((width * SDL_BITSPERPIXEL(format)) + 7) / 8;
pitch = (((Sint64)width * SDL_BITSPERPIXEL(format)) + 7) / 8;
}
pitch = (pitch + 3) & ~3; /* 4-byte aligning for speed */
return pitch;
@@ -59,11 +58,19 @@ SDL_Surface *
SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth,
Uint32 format)
{
Sint64 pitch;
SDL_Surface *surface;

/* The flags are no longer used, make the compiler happy */
(void)flags;

pitch = SDL_CalculatePitch(format, width);
if (pitch < 0 || pitch > SDL_MAX_SINT32) {
/* Overflow... */
SDL_OutOfMemory();
return NULL;
}

/* Allocate the surface */
surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface));
if (surface == NULL) {
@@ -78,7 +85,7 @@ SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth,
}
surface->w = width;
surface->h = height;
surface->pitch = SDL_CalculatePitch(format, width);
surface->pitch = (int)pitch;
SDL_SetClipRect(surface, NULL);

if (SDL_ISPIXELFORMAT_INDEXED(surface->format->format)) {

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