jbig2_decode_generic_template0_unopt(Jbig2Ctx *ctx,
                                     Jbig2Segment *segment,
                                     const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const int GBW = image->width;
    const int GBH = image->height;
    uint32_t CONTEXT;
    int x, y;
    bool bit;

    /* this version is generic and easy to understand, but very slow */

    for (y = 0; y < GBH; y++) {
        for (x = 0; x < GBW; x++) {
            CONTEXT = 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y) << 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
            CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
            CONTEXT |= jbig2_image_get_pixel(image, x - 4, y) << 3;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 4;
            CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 1) << 5;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 6;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 1) << 7;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 8;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 9;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[2], y + params->gbat[3]) << 10;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[4], y + params->gbat[5]) << 11;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 12;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 2) << 13;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 14;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[6], y + params->gbat[7]) << 15;
            bit = jbig2_arith_decode(as, &GB_stats[CONTEXT]);
            if (bit < 0)
                        return -1;
            jbig2_image_set_pixel(image, x, y, bit);
        }
    }
    return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.