reload v3 client authorization: Assertion !tor_mem_is_zero

When a v3 hidden service exists and an authorized client is added, Tor fails to reload the configuration.

== Steps to Reproduce

1. create a hidden service:

HiddenServiceDir /var/lib/tor/hidden_service/
HiddenServicePort 22 127.0.0.1

2. reload to create service (systemctl reload tor@default)

3. add a client

   content of ClientOnionAuthDir /var/lib/tor/client_auth:

   ClientOnionAuthDir /var/lib/tor/client_auth
   }}}
   

4. reload again (systemctl reload tor@default)

resulting crash:

{{{ Oct 20 00:48:52 rust Tor[8823]: tor_assertion_failed_(): Bug: ../src/feature/hs/hs_descriptor.c:2897: hs_desc_build_authorized_client: Assertion !tor_mem_is_zero((char *) descriptor_cookie, HS_DESC_DESCRIPTOR_COOKIE_LEN) failed; aborting. (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: Assertion !tor_mem_is_zero((char *) descriptor_cookie, HS_DESC_DESCRIPTOR_COOKIE_LEN) failed in hs_desc_build_authorized_client at ../src/feature/hs/hs_descriptor.c:2897. Stack trace: (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(log_backtrace_impl+0x47) [0x55eec9b04d97] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(tor_assertion_failed_+0x94) [0x55eec9b00344] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(hs_desc_build_authorized_client+0x2c7) [0x55eec9a1b337] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(+0x10707f) [0x55eec9a1d07f] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(hs_service_load_all_keys+0x2a0) [0x55eec9a20a30] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(set_options+0xeeb) [0x55eec9a8bcab] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(options_init_from_string+0x39c) [0x55eec9a8d87c] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(options_init_from_torrc+0x42e) [0x55eec9a8dece] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(+0x57d99) [0x55eec996dd99] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/lib/x86_64-linux-gnu/libevent-2.0.so.5(event_base_loop+0xef0) [0x7fe621423df0] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(do_main_loop+0xc5) [0x55eec9982665] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(tor_run_main+0x141e) [0x55eec997033e] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(tor_main+0x3a) [0x55eec996d64a] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(main+0x19) [0x55eec996d1c9] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf1) [0x7fe61fc7f2e1] (on Tor 0.3.5.3-alpha ) Oct 20 00:48:52 rust Tor[8823]: Bug: /usr/bin/tor(_start+0x2a) [0x55eec996d21a] (on Tor 0.3.5.3-alpha )

**Trac**:  
**Username**: pege