haukepetersen opened a new issue #556: att_svr memory corruption: entry_mem is 
freed without relocating existing entries
URL: https://github.com/apache/mynewt-nimble/issues/556
   # How to reproduce
   I initialized the GATT server in the following sequence:
   - init some included services, e.g.: `ble_svc_gap_init()`, 
   - start the GATT server: `ble_gatts_start()`
   - add some custom services: 'ble_gatts_count_cfg()`, `ble_gatts_add_svcs()`
   - (re)start the GATT server, to load additional services: 'ble_gatts_start()`
   This will lead to hard-faults on my platform (`nrf52dk`, RIOT, nimble 
   Used this RIOT branch: 
   NimBLE version: same on master and on 
   # Problem
   When initializing the GATT server, and thereby implicitly the ATT server, 
the ATT server frees and (re-)allocates the internal memory it uses for storing 
the servers entries (`ble_att_svr_entry_mem`). The problem is, that if 
`ble_gatts_start()` is called multiple times, the ATT server frees 
`ble_att_svr_entry_mem` which still contains valid entries. This freed memory 
is eventually re-used by other components in the system, leading to corrupted 
entries in the ATT server, and eventually making a system hard-fault...
   Simple test: add `assert((void *)entry >= (void *)ble_att_svr_entry_mem);` 
into `ble_att_svr_find_by_uuid()` -> this assertion is triggered when executing 
the sequence sketched above
   I am not so sure about a viable fix though: simply removing the 
`ble_att_svr_free_start_mem()` call from `ble_att_svr_start()` will fix this 
issue, but it sure enough opens a memory leak :-)
   I guess we probably must probably do something like this in 
   - allocate the new entry memory
   - move all existing entries from the old entry memory into the new one
   - and only then free the old entry memory again?

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