static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t old_l2_offset;
    uint64_t *l2_table = NULL;
    int64_t l2_offset;
    int ret;

    old_l2_offset = s->l1_table[l1_index];

    trace_qcow2_l2_allocate(bs, l1_index);

    /* allocate a new l2 entry */

    l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
    if (l2_offset < 0) {
        ret = l2_offset;
        goto fail;
    }

    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
    if (ret < 0) {
        goto fail;
    }

    /* allocate a new entry in the l2 cache */

    trace_qcow2_l2_allocate_get_empty(bs, l1_index);
    ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
    if (ret < 0) {
        goto fail;
    }

    l2_table = *table;

    if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
        /* if there was no old l2 table, clear the new table */
        memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
    } else {
        uint64_t* old_table;

        /* if there was an old l2 table, read it from the disk */
        BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
        ret = qcow2_cache_get(bs, s->l2_table_cache,
            old_l2_offset & L1E_OFFSET_MASK,
            (void**) &old_table);
        if (ret < 0) {
            goto fail;
        }

        memcpy(l2_table, old_table, s->cluster_size);

        ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table);
        if (ret < 0) {
            goto fail;
        }
    }

    /* write the l2 table to the file */
    BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);

    trace_qcow2_l2_allocate_write_l2(bs, l1_index);
    qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
    ret = qcow2_cache_flush(bs, s->l2_table_cache);
    if (ret < 0) {
        goto fail;
    }

    /* update the L1 entry */
    trace_qcow2_l2_allocate_write_l1(bs, l1_index);
    s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
    ret = qcow2_write_l1_entry(bs, l1_index);
    if (ret < 0) {
        goto fail;
    }

    *table = l2_table;
    trace_qcow2_l2_allocate_done(bs, l1_index, 0);
    return 0;

fail:
    trace_qcow2_l2_allocate_done(bs, l1_index, ret);
    if (l2_table != NULL) {
        qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
    }
    s->l1_table[l1_index] = old_l2_offset;
    if (l2_offset > 0) {
        qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
                            QCOW2_DISCARD_ALWAYS);
    }
    return ret;
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.