Fix null dereference in frida-server at startup

[mrmacete]

This happened on older iOS versions (happened to me on iPhone X on 16.1)

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000
Exception Codes: 0x0000000000000001, 0x0000000000000000

Triggered by Thread:  5


Thread 5 name:  gdbus
Thread 5 Crashed:
0   CoreFoundation                	       0x1968119d0 CFArrayGetCount + 8
1   frida-server                  	       0x104376164 frida_cf_array_iterator_construct + 92
2   frida-server                  	       0x1043779c4 frida_tunnel_interface_observer_handle_interface_changes + 92
3   frida-server                  	       0x104377868 frida_tunnel_interface_observer_real_start + 276
4   frida-server                  	       0x104372030 frida_web_service_do_start_co + 616
5   frida-server                  	       0x1043a9af8 g_task_return_now + 48
6   frida-server                  	       0x1043a9b38 complete_in_idle_cb + 20
7   frida-server                  	       0x104414cdc g_main_context_dispatch + 228
8   frida-server                  	       0x104414e9c g_main_context_iterate + 304
9   frida-server                  	       0x10441504c g_main_loop_run + 168
10  frida-server                  	       0x1043cd440 gdbus_shared_thread_func + 32
11  frida-server                  	       0x10442652c g_thread_proxy + 92
12  libsystem_pthread.dylib       	       0x1e2f48060 _pthread_start + 116
13  libsystem_pthread.dylib       	       0x1e2f46688 thread_start + 8

and prevented frida-server from starting up

[mrmacete]

this could be related to frida-server running in the System xpc domain rather than an iOS version issue, could it be a bigger problem?

[mrmacete]

i don't know the iceberg of this tip, but i can tell that the segfault is only reproducible in that scenario even on the same 16.1 device i have and doesn't happen if i run frida-server manually from the user domain

[oleavr]

this could be related to frida-server running in the System xpc domain rather than an iOS version issue, could it be a bigger problem?

Ooh yes, that's probably the root cause. We only need this functionality for iOS >= 17, so I wonder now if we still have the same issue there.