The c->in request counters are uint64_t, and can realistically go over 2**32 over a lifetime of a client. The c->in->replies map however uses unsigned int keys and the passed request numbers are silently truncated.
I haven't analyzed in depth what happens what it wraps around but it's probably nothing good.
The only user of the xcb_list.c map code is c->in->replies, so just change it to use uint64_t keys.
Signed-off-by: Ran Benita email@example.com