Infinite loop in net sockets shell command

[mwerschy]

Describe the bug

The net sockets command enters an infinite loop while printing sockets if too many have been opened. This seems to be caused by the way the socket object cores are reused:

zephyr/subsys/net/lib/sockets/socket_obj_core.c

Lines 69 to 71 in 47b07e5

	k_obj_core_init_and_link(K_OBJ_CORE(sock), &sock_obj_type);
	k_obj_core_stats_register(K_OBJ_CORE(sock), &sock->stats,
	sizeof(struct sock_obj_type_raw_stats));

Here the obj core is linked unconditionally, I believe it should instead only be linked and registered if sock->init_done is false. I can open a PR if that's sufficient, just wanted to get feedback first as I'm not familiar with this part of the code.

Impact

Annoyance – Minor irritation; no significant impact on usability or functionality.

[rlubos]

Here the obj core is linked unconditionally, I believe it should instead only be linked and registered if sock->init_done is false

I think you're right, I'm not super familiar with this part of the socket implementation, but k_obj_core_init_and_link() adds "obj cores" to a list, so when we open enough sockets to start reusing struct sock_obj, it may corrupt the list if used on such a "second-hand" sock obj (i.e. create loop by adding the same object the list twice). Feel free to send a PR if it solves the problem for you.