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Fixed overflow in surface pitch calculation

This commit is contained in:
Sam Lantinga 2020-06-17 08:44:45 -07:00
parent efe0935904
commit a7ff6e9615
1 changed files with 15 additions and 8 deletions
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23
src/video/SDL_surface.c
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@ -28,24 +28,23 @@
#include "SDL_yuv_c.h" #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 */ /* 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, SDL_COMPILE_TIME_ASSERT(surface_size_assumptions, sizeof(int) == sizeof(Sint32));
sizeof(int) == sizeof(Sint32) && sizeof(size_t) >= sizeof(Sint32));
/* Public routines */ /* Public routines */
/* /*
* Calculate the pad-aligned scanline width of a surface * Calculate the pad-aligned scanline width of a surface
*/ */
static int static Sint64
SDL_CalculatePitch(Uint32 format, int width) SDL_CalculatePitch(Uint32 format, int width)
{ {
int pitch; Sint64 pitch;
if (SDL_ISPIXELFORMAT_FOURCC(format) || SDL_BITSPERPIXEL(format) >= 8) { if (SDL_ISPIXELFORMAT_FOURCC(format) || SDL_BITSPERPIXEL(format) >= 8) {
pitch = (width * SDL_BYTESPERPIXEL(format)); pitch = ((Sint64)width * SDL_BYTESPERPIXEL(format));
} else { } 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 */ pitch = (pitch + 3) & ~3; /* 4-byte aligning for speed */
return pitch; return pitch;
@ -59,11 +58,19 @@ SDL_Surface *
SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth, SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth,
Uint32 format) Uint32 format)
{ {
Sint64 pitch;
SDL_Surface *surface; SDL_Surface *surface;
/* The flags are no longer used, make the compiler happy */ /* The flags are no longer used, make the compiler happy */
(void)flags; (void)flags;
pitch = SDL_CalculatePitch(format, width);
if (pitch < 0 || pitch > SDL_MAX_SINT32) {
/* Overflow... */
SDL_OutOfMemory();
return NULL;
}
/* Allocate the surface */ /* Allocate the surface */
surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface)); surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface));
if (surface == NULL) { if (surface == NULL) {
@ -78,7 +85,7 @@ SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth,
} }
surface->w = width; surface->w = width;
surface->h = height; surface->h = height;
surface->pitch = SDL_CalculatePitch(format, width); surface->pitch = (int)pitch;
SDL_SetClipRect(surface, NULL); SDL_SetClipRect(surface, NULL);
if (SDL_ISPIXELFORMAT_INDEXED(surface->format->format)) { if (SDL_ISPIXELFORMAT_INDEXED(surface->format->format)) {