Sorry Christian, I don't understand... On 04/21, Christian Brauner wrote: > > On Tue, Apr 21, 2020 at 11:28:47AM +0200, Oleg Nesterov wrote: > > On 04/21, Christian Brauner wrote: > > > > > > > - __group_send_sig_info(sig, &info, tsk->parent); > > > > + __send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false); > > > > > > So below you switch to __send_signal() but set the "force" argument to > > > to "false". > > > > it must be false, the signal is generated from the parent's namespace or > > its descendant > > > > > Before that, if the signal was generated from another pid > > > namespace and we fixed up si_pid and si_uid the "force" argument was set > > > to "true", > > > > before that the "force" argument could be falsely true by the same reason, > > task_pid_nr_ns(tsk, tsk->parent) can return 0 because "tsk" no longer have > > pids after __unhash_process(). > > As I said in my mail, looking at the codepath it seems safe. My question > was whether it is _always_ incorrectly false which I do think it is Again, it must be always "false", it can be incorrectly "true" and this too is fixed by Eric's patch. > because child subreapers can't come from outside the pid namespace. If > they could you could create a scenario where the signal is generated > from a sibling pid namespace in which case it would be correctly set to > true. not sure I understand, but probably the answer is "yes"... task and task->parent either live in the same namespace or the child's namespace is the descendant of task->parent's namespace. In both cases task_pid_nr_ns(tsk, tsk->parent) should return the valid pid_nr and "force" must be false. The corner case is release_task() when the last exiting sub-thread sends a signal on behalf of its ->group_leader, and at this point all the tsk's pid pointers are NULL, that is why "force" can be falsely "true". Oleg. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
