tree 7c95826a96a265f17fc493ab7fdce1bcc7db2753
parent 6db7778c81c7d90b41982dcf99272c65f208b6db
author Aleksander Wasaznik <aleksander.wasaznik@nordicsemi.no> 1632900181 +0200
committer Christopher Friedt <chrisfriedt@gmail.com> 1633135076 -0400

Bluetooth: Host: Fix resource leak in bt_gatt_unsubscribe

There are two simmilar functions for unsubscribing from GATT handles.

 - `gatt_sub_remove`, which is called on disconnect for every
 subscription will free the `subscriptions` entry when the entry
 represents no subscriptions.

 - `bt_gatt_unsubscribe`, called by the application, which forgets to
 free the `subscriptions` entry.

If all subscriptions grouped in a `subscriptions` entry are removed
using `bt_gatt_unsubscribe` before disconnect, there are no
subscriptions left to call `gatt_sub_remove` on. The `subscriptions`
entry is then never freed.

The above results in a resource leak of a `subscriptions` entry.

This fix makes explicit and enforces the invariant that there should not
be entries in `subscriptions` with an empty subscription list.

Fixes #38688

Signed-off-by: Aleksander Wasaznik <aleksander.wasaznik@nordicsemi.no>