[Bug 55000] New: wineserver crashes below save_all_subkeys after RegUnLoadKey

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=55000

Bug ID: 55000
           Summary: wineserver crashes below save_all_subkeys after
                    RegUnLoadKey
           Product: Wine
           Version: 8.9
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: wineserver
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

While trying to reproduce a crash in procexp64 I noticed a crash in
wineserver instead.

I think I found the reason in a call to `RegUnLoadKey(HKEY_USERS, ".Default")`,
which succeeds in wine while it should maybe not.

Program terminated with signal SIGSEGV, Segmentation fault.
208         struct object *parent = key->obj.name->parent;
(gdb) bt
#0  get_parent () at server/registry.c:208
#1  dump_path () at server/registry.c:226
#2  save_all_subkeys () at server/registry.c:2008
#3  save_branch (path="userdef.reg") at server/registry.c:2107
#4  save_branch () at server/registry.c:2134
#5  periodic_save () at server/registry.c:2131
#6  periodic_save () at server/registry.c:2124
#7  get_next_timeout () at server/fd.c:959
#8  main_loop_epoll () at server/fd.c:617
#9  main_loop () at server/fd.c:992
#10 main () at server/main.c:237
(gdb) print key->obj.name
$3 = (struct object_name *) 0x0

The "name" member got set to NULL here before in wineserver:
424         obj->name = NULL;
(rr) bt
#0   unlink_named_object () at server/object.c:424
#1   delete_key () at server/registry.c:1089
#2   req_unload_registry () at server/registry.c:2363
#3   call_req_handler () at server/request.c:305
#4   read_request () at server/request.c:360

With the request originating at process side here:

#14 wine_server_call () at dlls/ntdll/unix/server.c:307
#15 NtUnloadKey () at dlls/ntdll/unix/registry.c:767
#16 __wine_syscall_dispatcher ()