alpine 3.6
buffer weakness #211


Weakness Breakdown


Buffer overflows are one of the most well-known software vulnerabilities. Even though most developers know what buffer overflows are, attacks against the vulnerabilities are common in both legacy and newer applications. A classic buffer overflow exploit begins with the attacker sending data to a program, which it then stores in an undersized stack buffer. Besides stack buffer overflows, other kinds of buffer overflows include heap overflows, off-by-one errors and many others. Learn more about buffer overflows on OWASP attack index.

Warning code(s):

Easily used incorrectly.

File Name:



The highlighted line of code below is the trigger point of this particular Alpine 3.6 buffer weakness.

    // cues start
    av_dict_set_int(&s->streams[0]->metadata, CUES_START, cues_start, 0);

    // cues end
    av_dict_set_int(&s->streams[0]->metadata, CUES_END, cues_end, 0);

    // bandwidth
    bandwidth = webm_dash_manifest_compute_bandwidth(s, cues_start);
    if (bandwidth < 0) return -1;
    av_dict_set_int(&s->streams[0]->metadata, BANDWIDTH, bandwidth, 0);

    // check if all clusters start with key frames
    av_dict_set_int(&s->streams[0]->metadata, CLUSTER_KEYFRAME, webm_clusters_start_with_keyframe(s), 0);

    // store cue point timestamps as a comma separated list for checking subsegment alignment in
    // the muxer. assumes that each timestamp cannot be more than 20 characters long.
    buf = av_malloc_array(s->streams[0]->nb_index_entries, 20 * sizeof(char));
    if (!buf) return -1;
    strcpy(buf, "");
    for (i = 0; i < s->streams[0]->nb_index_entries; i++) {
        snprintf(buf, (i + 1) * 20 * sizeof(char),
                 "%s%" PRId64, buf, s->streams[0]->index_entries[i].timestamp);
        if (i != s->streams[0]->nb_index_entries - 1)
            strncat(buf, ",", sizeof(char));
    av_dict_set(&s->streams[0]->metadata, CUE_TIMESTAMPS, buf, 0);

    return 0;

static int webm_dash_manifest_read_header(AVFormatContext *s)
    char *buf;
    int ret = matroska_read_header(s);
    MatroskaTrack *tracks;
    MatroskaDemuxContext *matroska = s->priv_data;
    if (ret) {
        av_log(s, AV_LOG_ERROR, "Failed to read file headers\n");
        return -1;
    if (!s->nb_streams) {
        av_log(s, AV_LOG_ERROR, "No streams found\n");

    if (!matroska->is_live) {
        buf = av_asprintf("%g", matroska->duration); 

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