static int decode_slice(AVCodecContext *c, void *arg)
{
    FFV1Context *fs   = *(void **)arg;
    FFV1Context *f    = fs->avctx->priv_data;
    int width, height, x, y, ret;
    const int ps      = av_pix_fmt_desc_get(c->pix_fmt)->comp[0].step_minus1 + 1;
    AVFrame * const p = f->cur;
    int i, si;

    for( si=0; fs != f->slice_context[si]; si ++)
        ;

    if(f->fsrc && !p->key_frame)
        ff_thread_await_progress(&f->last_picture, si, 0);

    if(f->fsrc && !p->key_frame) {
        FFV1Context *fssrc = f->fsrc->slice_context[si];
        FFV1Context *fsdst = f->slice_context[si];
        av_assert1(fsdst->plane_count == fssrc->plane_count);
        av_assert1(fsdst == fs);

        if (!p->key_frame)
            fsdst->slice_damaged |= fssrc->slice_damaged;

        for (i = 0; i < f->plane_count; i++) {
            PlaneContext *psrc = &fssrc->plane[i];
            PlaneContext *pdst = &fsdst->plane[i];

            av_free(pdst->state);
            av_free(pdst->vlc_state);
            memcpy(pdst, psrc, sizeof(*pdst));
            pdst->state = NULL;
            pdst->vlc_state = NULL;

            if (fssrc->ac) {
                pdst->state = av_malloc(CONTEXT_SIZE * psrc->context_count);
                memcpy(pdst->state, psrc->state, CONTEXT_SIZE * psrc->context_count);
            } else {
                pdst->vlc_state = av_malloc(sizeof(*pdst->vlc_state) * psrc->context_count);
                memcpy(pdst->vlc_state, psrc->vlc_state, sizeof(*pdst->vlc_state) * psrc->context_count);
            }
        }
    }

    if (f->version > 2) {
        if (ffv1_init_slice_state(f, fs) < 0)
            return AVERROR(ENOMEM);
        if (decode_slice_header(f, fs) < 0) {
            fs->slice_damaged = 1;
            return AVERROR_INVALIDDATA;
        }
    }
    if ((ret = ffv1_init_slice_state(f, fs)) < 0)
        return ret;
    if (f->cur->key_frame)
        ffv1_clear_slice_state(f, fs);

    width  = fs->slice_width;
    height = fs->slice_height;
    x      = fs->slice_x;
    y      = fs->slice_y;

    if (!fs->ac) {
        if (f->version == 3 && f->micro_version > 1 || f->version > 3)
            get_rac(&fs->c, (uint8_t[]) { 129 });
        fs->ac_byte_count = f->version > 2 || (!x && !y) ? fs->c.bytestream - fs->c.bytestream_start - 1 : 0;
        init_get_bits(&fs->gb,
                      fs->c.bytestream_start + fs->ac_byte_count,
                      (fs->c.bytestream_end - fs->c.bytestream_start - fs->ac_byte_count) * 8);
    }

    av_assert1(width && height);
    if (f->colorspace == 0) {
        const int chroma_width  = FF_CEIL_RSHIFT(width,  f->chroma_h_shift);
        const int chroma_height = FF_CEIL_RSHIFT(height, f->chroma_v_shift);
        const int cx            = x >> f->chroma_h_shift;
        const int cy            = y >> f->chroma_v_shift;
        decode_plane(fs, p->data[0] + ps*x + y*p->linesize[0], width, height, p->linesize[0], 0);

        if (f->chroma_planes) {
            decode_plane(fs, p->data[1] + ps*cx+cy*p->linesize[1], chroma_width, chroma_height, p->linesize[1], 1);
            decode_plane(fs, p->data[2] + ps*cx+cy*p->linesize[2], chroma_width, chroma_height, p->linesize[2], 1);
        }
        if (fs->transparency)
            decode_plane(fs, p->data[3] + ps*x + y*p->linesize[3], width, height, p->linesize[3], 2);
    } else {
        uint8_t *planes[3] = { p->data[0] + ps * x + y * p->linesize[0],
                               p->data[1] + ps * x + y * p->linesize[1],
                               p->data[2] + ps * x + y * p->linesize[2] };
        decode_rgb_frame(fs, planes, width, height, p->linesize);
    }
    if (fs->ac && f->version > 2) {
        int v;
        get_rac(&fs->c, (uint8_t[]) { 129 });
        v = fs->c.bytestream_end - fs->c.bytestream - 2 - 5*f->ec;
        if (v) {
            av_log(f->avctx, AV_LOG_ERROR, "bytestream end mismatching by %d\n", v);
            fs->slice_damaged = 1;
        }
    }

    emms_c();

    ff_thread_report_progress(&f->picture, si, 0);

    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.