int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
{
    BDRVQcowState *s = bs->opaque;
    QCowSnapshot *new_snapshot_list = NULL;
    QCowSnapshot *old_snapshot_list = NULL;
    QCowSnapshot sn1, *sn = &sn1;
    int i, ret;
    uint64_t *l1_table = NULL;
    int64_t l1_table_offset;

    if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) {
        return -EFBIG;
    }

    memset(sn, 0, sizeof(*sn));

    /* Generate an ID if it wasn't passed */
    if (sn_info->id_str[0] == '\0') {
        find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
    }

    /* Check that the ID is unique */
    if (find_snapshot_by_id_and_name(bs, sn_info->id_str, NULL) >= 0) {
        return -EEXIST;
    }

    /* Populate sn with passed data */
    sn->id_str = g_strdup(sn_info->id_str);
    sn->name = g_strdup(sn_info->name);

    sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
    sn->vm_state_size = sn_info->vm_state_size;
    sn->date_sec = sn_info->date_sec;
    sn->date_nsec = sn_info->date_nsec;
    sn->vm_clock_nsec = sn_info->vm_clock_nsec;

    /* Allocate the L1 table of the snapshot and copy the current one there. */
    l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
    if (l1_table_offset < 0) {
        ret = l1_table_offset;
        goto fail;
    }

    sn->l1_table_offset = l1_table_offset;
    sn->l1_size = s->l1_size;

    l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
    for(i = 0; i < s->l1_size; i++) {
        l1_table[i] = cpu_to_be64(s->l1_table[i]);
    }

    ret = qcow2_pre_write_overlap_check(bs, 0, sn->l1_table_offset,
                                        s->l1_size * sizeof(uint64_t));
    if (ret < 0) {
        goto fail;
    }

    ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
                      s->l1_size * sizeof(uint64_t));
    if (ret < 0) {
        goto fail;
    }

    g_free(l1_table);
    l1_table = NULL;

    /*
     * Increase the refcounts of all clusters and make sure everything is
     * stable on disk before updating the snapshot table to contain a pointer
     * to the new L1 table.
     */
    ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
    if (ret < 0) {
        goto fail;
    }

    /* Append the new snapshot to the snapshot list */
    new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
    if (s->snapshots) {
        memcpy(new_snapshot_list, s->snapshots,
               s->nb_snapshots * sizeof(QCowSnapshot));
        old_snapshot_list = s->snapshots;
    }
    s->snapshots = new_snapshot_list;
    s->snapshots[s->nb_snapshots++] = *sn;

    ret = qcow2_write_snapshots(bs);
    if (ret < 0) {
        g_free(s->snapshots);
        s->snapshots = old_snapshot_list;
        s->nb_snapshots--;
        goto fail;
    }

    g_free(old_snapshot_list);

    /* The VM state isn't needed any more in the active L1 table; in fact, it
     * hurts by causing expensive COW for the next snapshot. */
    qcow2_discard_clusters(bs, qcow2_vm_state_offset(s),
                           align_offset(sn->vm_state_size, s->cluster_size)
                                >> BDRV_SECTOR_BITS,
                           QCOW2_DISCARD_NEVER);

#ifdef DEBUG_ALLOC
    {
      BdrvCheckResult result = {0};
      qcow2_check_refcounts(bs, &result, 0);
    }
#endif
    return 0;

fail:
    g_free(sn->id_str);
    g_free(sn->name);
    g_free(l1_table);

    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.