static int vp7_decode_frame_header(VP8Context *s, const uint8_t *buf, int buf_size)
{
    VP56RangeCoder *c = &s->c;
    int part1_size, hscale, vscale, i, j, ret;
    int width  = s->avctx->width;
    int height = s->avctx->height;

    if (buf_size < 4) {
        return AVERROR_INVALIDDATA;
    }

    s->profile = (buf[0] >> 1) & 7;
    if (s->profile > 1) {
        avpriv_request_sample(s->avctx, "Unknown profile %d", s->profile);
        return AVERROR_INVALIDDATA;
    }

    s->keyframe  = !(buf[0] & 1);
    s->invisible = 0;
    part1_size   = AV_RL24(buf) >> 4;

    if (buf_size < 4 - s->profile + part1_size) {
        av_log(s->avctx, AV_LOG_ERROR, "Buffer size %d is too small, needed : %d\n", buf_size, 4 - s->profile + part1_size);
        return AVERROR_INVALIDDATA;
    }

    buf      += 4 - s->profile;
    buf_size -= 4 - s->profile;

    memcpy(s->put_pixels_tab, s->vp8dsp.put_vp8_epel_pixels_tab, sizeof(s->put_pixels_tab));

    ret = ff_vp56_init_range_decoder(c, buf, part1_size);
    if (ret < 0)
        return ret;
    buf      += part1_size;
    buf_size -= part1_size;

    /* A. Dimension information (keyframes only) */
    if (s->keyframe) {
        width  = vp8_rac_get_uint(c, 12);
        height = vp8_rac_get_uint(c, 12);
        hscale = vp8_rac_get_uint(c, 2);
        vscale = vp8_rac_get_uint(c, 2);
        if (hscale || vscale)
            avpriv_request_sample(s->avctx, "Upscaling");

        s->update_golden = s->update_altref = VP56_FRAME_CURRENT;
        vp78_reset_probability_tables(s);
        memcpy(s->prob->pred16x16, vp8_pred16x16_prob_inter,
               sizeof(s->prob->pred16x16));
        memcpy(s->prob->pred8x8c, vp8_pred8x8c_prob_inter,
               sizeof(s->prob->pred8x8c));
        for (i = 0; i < 2; i++)
            memcpy(s->prob->mvc[i], vp7_mv_default_prob[i],
                   sizeof(vp7_mv_default_prob[i]));
        memset(&s->segmentation, 0, sizeof(s->segmentation));
        memset(&s->lf_delta, 0, sizeof(s->lf_delta));
        memcpy(s->prob[0].scan, ff_zigzag_scan, sizeof(s->prob[0].scan));
    }

    if (s->keyframe || s->profile > 0)
        memset(s->inter_dc_pred, 0 , sizeof(s->inter_dc_pred));

    /* B. Decoding information for all four macroblock-level features */
    for (i = 0; i < 4; i++) {
        s->feature_enabled[i] = vp8_rac_get(c);
        if (s->feature_enabled[i]) {
             s->feature_present_prob[i] = vp8_rac_get_uint(c, 8);

             for (j = 0; j < 3; j++)
                 s->feature_index_prob[i][j] =
                     vp8_rac_get(c) ? vp8_rac_get_uint(c, 8) : 255;

             if (vp7_feature_value_size[s->profile][i])
                 for (j = 0; j < 4; j++)
                     s->feature_value[i][j] =
                        vp8_rac_get(c) ? vp8_rac_get_uint(c, vp7_feature_value_size[s->profile][i]) : 0;
        }
    }

    s->segmentation.enabled    = 0;
    s->segmentation.update_map = 0;
    s->lf_delta.enabled        = 0;

    s->num_coeff_partitions = 1;
    ret = ff_vp56_init_range_decoder(&s->coeff_partition[0], buf, buf_size);
    if (ret < 0)
        return ret;

    if (!s->macroblocks_base || /* first frame */
        width != s->avctx->width || height != s->avctx->height ||
        (width + 15) / 16 != s->mb_width || (height + 15) / 16 != s->mb_height) {
        if ((ret = vp7_update_dimensions(s, width, height)) < 0)
            return ret;
    }

    /* C. Dequantization indices */
    vp7_get_quants(s);

    /* D. Golden frame update flag (a Flag) for interframes only */
    if (!s->keyframe) {
        s->update_golden = vp8_rac_get(c) ? VP56_FRAME_CURRENT : VP56_FRAME_NONE;
        s->sign_bias[VP56_FRAME_GOLDEN] = 0;
    }

    s->update_last          = 1;
    s->update_probabilities = 1;
    s->fade_present         = 1;

    if (s->profile > 0) {
        s->update_probabilities = vp8_rac_get(c);
        if (!s->update_probabilities)
            s->prob[1] = s->prob[0];

        if (!s->keyframe)
            s->fade_present = vp8_rac_get(c);
    }

    /* E. Fading information for previous frame */
    if (s->fade_present && vp8_rac_get(c)) {
        if ((ret = vp7_fade_frame(s ,c)) < 0)
            return ret;
    }

    /* F. Loop filter type */
    if (!s->profile)
        s->filter.simple = vp8_rac_get(c);

    /* G. DCT coefficient ordering specification */
    if (vp8_rac_get(c))
        for (i = 1; i < 16; i++)
            s->prob[0].scan[i] = ff_zigzag_scan[vp8_rac_get_uint(c, 4)];

    /* H. Loop filter levels  */
    if (s->profile > 0)
        s->filter.simple = vp8_rac_get(c);
    s->filter.level     = vp8_rac_get_uint(c, 6);
    s->filter.sharpness = vp8_rac_get_uint(c, 3);

    /* I. DCT coefficient probability update; 13.3 Token Probability Updates */
    vp78_update_probability_tables(s);

    s->mbskip_enabled = 0;

    /* J. The remaining frame header data occurs ONLY FOR INTERFRAMES */
    if (!s->keyframe) {
        s->prob->intra  = vp8_rac_get_uint(c, 8);
        s->prob->last   = vp8_rac_get_uint(c, 8);
        vp78_update_pred16x16_pred8x8_mvc_probabilities(s, VP7_MVC_SIZE);
    }

    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.