jbig2_decode_pattern_dict(Jbig2Ctx *ctx, Jbig2Segment *segment,
                          const Jbig2PatternDictParams *params, const byte *data, const size_t size, Jbig2ArithCx *GB_stats)
{
    Jbig2PatternDict *hd = NULL;
    Jbig2Image *image = NULL;
    Jbig2GenericRegionParams rparams;
    int code = 0;

    /* allocate the collective image */
    image = jbig2_image_new(ctx, params->HDPW * (params->GRAYMAX + 1), params->HDPH);
    if (image == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate collective bitmap for halftone dict!");
        return NULL;
    }

    /* fill out the generic region decoder parameters */
    rparams.MMR = params->HDMMR;
    rparams.GBTEMPLATE = params->HDTEMPLATE;
    rparams.TPGDON = 0;         /* not used if HDMMR = 1 */
    rparams.USESKIP = 0;
    rparams.gbat[0] = -(int8_t) params->HDPW;
    rparams.gbat[1] = 0;
    rparams.gbat[2] = -3;
    rparams.gbat[3] = -1;
    rparams.gbat[4] = 2;
    rparams.gbat[5] = -2;
    rparams.gbat[6] = -2;
    rparams.gbat[7] = -2;

    if (params->HDMMR) {
        code = jbig2_decode_generic_mmr(ctx, segment, &rparams, data, size, image);
    } else {
        Jbig2WordStream *ws = jbig2_word_stream_buf_new(ctx, data, size);

        if (ws != NULL) {
            Jbig2ArithState *as = jbig2_arith_new(ctx, ws);

            if (as != NULL) {
                code = jbig2_decode_generic_region(ctx, segment, &rparams, as, image, GB_stats);
            } else {
                code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate storage for as in halftone dict!");
            }

            jbig2_free(ctx->allocator, as);
            jbig2_word_stream_buf_free(ctx, ws);
        } else {
            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate storage for ws in halftone dict!");
        }
    }

    if (code == 0)
        hd = jbig2_hd_new(ctx, params, image);
    jbig2_image_release(ctx, image);

    return hd;
}

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.