static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
{
    const uint8_t *buf  = avpkt->data;
    int buf_size        = avpkt->size;
    FFV1Context *f      = avctx->priv_data;
    RangeCoder *const c = &f->slice_context[0]->c;
    int i, ret;
    uint8_t keystate = 128;
    const uint8_t *buf_p;
    AVFrame *p;

    if (f->last_picture.f)
        ff_thread_release_buffer(avctx, &f->last_picture);
    FFSWAP(ThreadFrame, f->picture, f->last_picture);

    f->cur = p = f->picture.f;

    if (f->version < 3 && avctx->field_order > AV_FIELD_PROGRESSIVE) {
        /* we have interlaced material flagged in container */
        p->interlaced_frame = 1;
        if (avctx->field_order == AV_FIELD_TT || avctx->field_order == AV_FIELD_TB)
            p->top_field_first = 1;
    }

    f->avctx = avctx;
    ff_init_range_decoder(c, buf, buf_size);
    ff_build_rac_states(c, 0.05 * (1LL << 32), 256 - 8);

    p->pict_type = AV_PICTURE_TYPE_I; //FIXME I vs. P
    if (get_rac(c, &keystate)) {
        p->key_frame    = 1;
        f->key_frame_ok = 0;
        if ((ret = read_header(f)) < 0)
            return ret;
        f->key_frame_ok = 1;
    } else {
        if (!f->key_frame_ok) {
            av_log(avctx, AV_LOG_ERROR,
                   "Cannot decode non-keyframe without valid keyframe\n");
            return AVERROR_INVALIDDATA;
        }
        p->key_frame = 0;
    }

    if ((ret = ff_thread_get_buffer(avctx, &f->picture, AV_GET_BUFFER_FLAG_REF)) < 0)
        return ret;

    if (avctx->debug & FF_DEBUG_PICT_INFO)
        av_log(avctx, AV_LOG_DEBUG, "ver:%d keyframe:%d coder:%d ec:%d slices:%d bps:%d\n",
               f->version, p->key_frame, f->ac, f->ec, f->slice_count, f->avctx->bits_per_raw_sample);

    ff_thread_finish_setup(avctx);

    buf_p = buf + buf_size;
    for (i = f->slice_count - 1; i >= 0; i--) {
        FFV1Context *fs = f->slice_context[i];
        int trailer = 3 + 5*!!f->ec;
        int v;

        if (i || f->version > 2) v = AV_RB24(buf_p-trailer) + trailer;
        else                     v = buf_p - c->bytestream_start;
        if (buf_p - c->bytestream_start < v) {
            av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n");
            return AVERROR_INVALIDDATA;
        }
        buf_p -= v;

        if (f->ec) {
            unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0, buf_p, v);
            if (crc) {
                int64_t ts = avpkt->pts != AV_NOPTS_VALUE ? avpkt->pts : avpkt->dts;
                av_log(f->avctx, AV_LOG_ERROR, "CRC mismatch %X!", crc);
                if (ts != AV_NOPTS_VALUE && avctx->pkt_timebase.num) {
                    av_log(f->avctx, AV_LOG_ERROR, "at %f seconds\n", ts*av_q2d(avctx->pkt_timebase));
                } else if (ts != AV_NOPTS_VALUE) {
                    av_log(f->avctx, AV_LOG_ERROR, "at %"PRId64"\n", ts);
                } else {
                    av_log(f->avctx, AV_LOG_ERROR, "\n");
                }
                fs->slice_damaged = 1;
            }
        }

        if (i) {
            ff_init_range_decoder(&fs->c, buf_p, v);
        } else
            fs->c.bytestream_end = (uint8_t *)(buf_p + v);

        fs->avctx = avctx;
        fs->cur = p;
    }

    avctx->execute(avctx,
                   decode_slice,
                   &f->slice_context[0],
                   NULL,
                   f->slice_count,
                   sizeof(void*));

    for (i = f->slice_count - 1; i >= 0; i--) {
        FFV1Context *fs = f->slice_context[i];
        int j;
        if (fs->slice_damaged && f->last_picture.f->data[0]) {
            const uint8_t *src[4];
            uint8_t *dst[4];
            ff_thread_await_progress(&f->last_picture, INT_MAX, 0);
            for (j = 0; j < 4; j++) {
                int sh = (j==1 || j==2) ? f->chroma_h_shift : 0;
                int sv = (j==1 || j==2) ? f->chroma_v_shift : 0;
                dst[j] = p->data[j] + p->linesize[j]*
                         (fs->slice_y>>sv) + (fs->slice_x>>sh);
                src[j] = f->last_picture.f->data[j] + f->last_picture.f->linesize[j]*
                         (fs->slice_y>>sv) + (fs->slice_x>>sh);
            }
            av_image_copy(dst, p->linesize, (const uint8_t **)src,
                          f->last_picture.f->linesize,
                          avctx->pix_fmt,
                          fs->slice_width,
                          fs->slice_height);
        }
    }
    ff_thread_report_progress(&f->picture, INT_MAX, 0);

    f->picture_number++;

    if (f->last_picture.f)
        ff_thread_release_buffer(avctx, &f->last_picture);
    f->cur = NULL;
    if ((ret = av_frame_ref(data, f->picture.f)) < 0)
        return ret;

    *got_frame = 1;

    return buf_size;
}

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.