static int jpeg2000_decode_packets(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int ret = 0;
    int layno, reslevelno, compno, precno, ok_reslevel;
    int x, y;

    s->bit_index = 8;
    switch (tile->codsty[0].prog_order) {
    case JPEG2000_PGOD_RLCP:
        avpriv_request_sample(s->avctx, "Progression order RLCP");

    case JPEG2000_PGOD_LRCP:
        for (layno = 0; layno < tile->codsty[0].nlayers; layno++) {
            ok_reslevel = 1;
            for (reslevelno = 0; ok_reslevel; reslevelno++) {
                ok_reslevel = 0;
                for (compno = 0; compno < s->ncomponents; compno++) {
                    Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                    Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;
                    if (reslevelno < codsty->nreslevels) {
                        Jpeg2000ResLevel *rlevel = tile->comp[compno].reslevel +
                                                reslevelno;
                        ok_reslevel = 1;
                        for (precno = 0; precno < rlevel->num_precincts_x * rlevel->num_precincts_y; precno++)
                            if ((ret = jpeg2000_decode_packet(s,
                                                              codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_CPRL:
        for (compno = 0; compno < s->ncomponents; compno++) {
            Jpeg2000CodingStyle *codsty = tile->codsty + compno;
            Jpeg2000QuantStyle *qntsty  = tile->qntsty + compno;

            /* Set bit stream buffer address according to tile-part.
             * For DCinema one tile-part per component, so can be
             * indexed by component. */
            s->g = tile->tile_part[compno].tpg;

            /* Position loop (y axis)
             * TODO: Automate computing of step 256.
             * Fixed here, but to be computed before entering here. */
            for (y = 0; y < s->height; y += 256) {
                /* Position loop (y axis)
                 * TODO: automate computing of step 256.
                 * Fixed here, but to be computed before entering here. */
                for (x = 0; x < s->width; x += 256) {
                    for (reslevelno = 0; reslevelno < codsty->nreslevels; reslevelno++) {
                        uint16_t prcx, prcy;
                        uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                        Jpeg2000ResLevel *rlevel = tile->comp[compno].reslevel + reslevelno;

                        if (!((y % (1 << (rlevel->log2_prec_height + reducedresno)) == 0) ||
                              (y == 0))) // TODO: 2nd condition simplified as try0 always =0 for dcinema
                            continue;

                        if (!((x % (1 << (rlevel->log2_prec_width + reducedresno)) == 0) ||
                              (x == 0))) // TODO: 2nd condition simplified as try0 always =0 for dcinema
                            continue;

                        prcx   = ff_jpeg2000_ceildivpow2(x, reducedresno) >> rlevel->log2_prec_width;
                        prcy   = ff_jpeg2000_ceildivpow2(y, reducedresno) >> rlevel->log2_prec_height;
                        precno = prcx + rlevel->num_precincts_x * prcy;
                        for (layno = 0; layno < tile->codsty[0].nlayers; layno++) {
                            if ((ret = jpeg2000_decode_packet(s, codsty, rlevel,
                                                              precno, layno,
                                                              qntsty->expn + (reslevelno ? 3 * (reslevelno - 1) + 1 : 0),
                                                              qntsty->nguardbits)) < 0)
                                return ret;
                        }
                    }
                }
            }
        }
        break;

    case JPEG2000_PGOD_RPCL:
        avpriv_request_sample(s->avctx, "Progression order RPCL");
        ret = AVERROR_PATCHWELCOME;
        break;

    case JPEG2000_PGOD_PCRL:
        avpriv_request_sample(s->avctx, "Progression order PCRL");
        ret = AVERROR_PATCHWELCOME;
        break;

    default:
        break;
    }

    /* EOC marker reached */
    bytestream2_skip(&s->g, 2);

    return ret;
}

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.