SIGSEGV in mir::frontend::WlSeat::ConfigObserver::device_changed on input device disconnection

[Saviq]

#0  0x000075eb2898768c in mir::frontend::WlSeat::ConfigObserver::device_changed (this=0x5c6fbdb4c9a0, device=...) at /root/parts/mir/src/src/server/frontend_wayland/wl_seat.cpp:120
        keyboard_config = {value_ = {impl = {_M_t = {<std::__uniq_ptr_impl<MirKeyboardConfig::Implementation, std::default_delete<MirKeyboardConfig::Implementation> >> = {_M_t = {<std::_Tuple_impl<0, MirKeyboardConfig::Implementation*, std::default_delete<MirKeyboardConfig::Implementation> >> = {<std::_Tuple_impl<1, std::default_delete<MirKeyboardConfig::Implementation> >> = {<std::_Head_base<1, std::default_delete<MirKeyboardConfig::Implementation>, true>> = {_M_head_impl = {<No data fields>}}, <No data fields>}, <std::_Head_base<0, MirKeyboardConfig::Implementation*, false>> = {_M_head_impl = 0x7ffe491d74d0}, <No data fields>}, <No data fields>}}, <No data fields>}}}, is_set_ = 48}
#1  0x000075eb2875a770 in operator() (__closure=0x75ea9c0dd8e0, observer=...) at /root/parts/mir/src/src/server/input/default_input_device_hub.cpp:179
        dev = @0x5c6fbdb9d3a0: {<std::__shared_ptr<mir::input::Device, (__gnu_cxx::_Lock_policy)2>> = {<std::__shared_ptr_access<mir::input::Device, (__gnu_cxx::_Lock_policy)2, false, false>> = {<No data fields>}, _M_ptr = 0x0, _M_refcount = {_M_pi = 0x0}}, <No data fields>}
        __for_range = @0x5c6fbdba3e60: {<std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >> = {_M_impl = {<std::allocator<std::shared_ptr<mir::input::Device> >> = {<std::__new_allocator<std::shared_ptr<mir::input::Device> >> = {<No data fields>}, <No data fields>}, <std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >::_Vector_impl_data> = {_M_start = 0x5c6fbdb9d3a0, _M_finish = 0x5c6fbdb9d3b0, _M_end_of_storage = 0x5c6fbdb9d3b0}, <No data fields>}}, <No data fields>}
        __for_begin = {_M_current = 0x5c6fbdb9d3a0}
        __for_end = {_M_current = 0x5c6fbdb9d3b0}
        added = @0x5c6fbdba3e48: {<std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >> = {_M_impl = {<std::allocator<std::shared_ptr<mir::input::Device> >> = {<std::__new_allocator<std::shared_ptr<mir::input::Device> >> = {<No data fields>}, <No data fields>}, <std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >::_Vector_impl_data> = {_M_start = 0x0, _M_finish = 0x0, _M_end_of_storage = 0x0}, <No data fields>}}, <No data fields>}
        changed = @0x5c6fbdba3e60: {<std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >> = {_M_impl = {<std::allocator<std::shared_ptr<mir::input::Device> >> = {<std::__new_allocator<std::shared_ptr<mir::input::Device> >> = {<No data fields>}, <No data fields>}, <std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >::_Vector_impl_data> = {_M_start = 0x5c6fbdb9d3a0, _M_finish = 0x5c6fbdb9d3b0, _M_end_of_storage = 0x5c6fbdb9d3b0}, <No data fields>}}, <No data fields>}
        removed = @0x5c6fbdba3e78: {<std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >> = {_M_impl = {<std::allocator<std::shared_ptr<mir::input::Device> >> = {<std::__new_allocator<std::shared_ptr<mir::input::Device> >> = {<No data fields>}, <No data fields>}, <std::_Vector_base<std::shared_ptr<mir::input::Device>, std::allocator<std::shared_ptr<mir::input::Device> > >::_Vector_impl_data> = {_M_start = 0x0, _M_finish = 0x0, _M_end_of_storage = 0x0}, <No data fields>}}, <No data fields>}
#2  0x000075eb28761439 in std::__invoke_impl<void, mir::input::ExternalInputDeviceHub::Internal::changes_complete()::<lambda()>::<lambda(const std::shared_ptr<mir::input::InputDeviceObserver>&)>&, const std::shared_ptr<mir::input::InputDeviceObserver>&>(std::__invoke_other, struct {...} &) (__f=...) at /usr/include/c++/13/bits/invoke.h:61
No locals.
#3  0x000075eb2875fd97 in std::__invoke_r<void, mir::input::ExternalInputDeviceHub::Internal::changes_complete()::<lambda()>::<lambda(const std::shared_ptr<mir::input::InputDeviceObserver>&)>&, const std::shared_ptr<mir::input::InputDeviceObserver>&>(struct {...} &) (__fn=...) at /usr/include/c++/13/bits/invoke.h:111
No locals.
#4  0x000075eb2875eb7e in std::_Function_handler<void(const std::shared_ptr<mir::input::InputDeviceObserver>&), mir::input::ExternalInputDeviceHub::Internal::changes_complete()::<lambda()>::<lambda(const std::shared_ptr<mir::input::InputDeviceObserver>&)> >::_M_invoke(const std::_Any_data &, const std::shared_ptr<mir::input::InputDeviceObserver> &) (__functor=..., __args#0=...) at /usr/include/c++/13/bits/std_function.h:290
No locals.
#5  0x000075eb2876c055 in std::function<void(std::shared_ptr<mir::input::InputDeviceObserver> const&)>::operator() (this=0x7ffe491d76f0, __args#0=...) at /usr/include/c++/13/bits/std_function.h:591
No locals.
#6  0x000075eb287689ea in mir::ThreadSafeList<std::shared_ptr<mir::input::InputDeviceObserver> >::for_each (this=0x5c6fbd8cf8a8, f=...) at /root/parts/mir/src/src/include/common/mir/thread_safe_list.h:78
        copy_of_element = {<std::__shared_ptr<mir::input::InputDeviceObserver, (__gnu_cxx::_Lock_policy)2>> = {<std::__shared_ptr_access<mir::input::InputDeviceObserver, (__gnu_cxx::_Lock_policy)2, false, false>> = {<No data fields>}, _M_ptr = 0x5c6fbdb4c9a0, _M_refcount = {_M_pi = 0x5c6fbdb4c990}}, <No data fields>}
        lock = {mutex = @0x5c6fbd8cf8a8}
        current_item = 0x5c6fbd8cf8a8

gdb.txt

[AlanGriffiths]

You just unplug an input device and "boom"?

[Saviq]

On a VT, yes.

[AlanGriffiths]

Weird. I regularly plug/unplug a docking station without trouble.

But I found a USB mouse and... "boom!"