On Wed, Aug 14, 2019 at 02:50:12PM +0200, Oleg Nesterov wrote: > On 08/14, Christian Brauner wrote: > > > > On Wed, Aug 14, 2019 at 02:29:10PM +0200, Oleg Nesterov wrote: > > > On 08/14, [email protected] wrote: > > > > > > > > case P_PGID: > > > > type = PIDTYPE_PGID; > > > > - if (upid <= 0) > > > > + if (upid < 0) > > > > return -EINVAL; > > > > + > > > > + if (upid == 0) > > > > + pid = get_pid(task_pgrp(current)); > > > > > > this needs rcu lock or tasklist_lock, this can race with another thread > > > doing sys_setpgid/setsid (see change_pid(PIDTYPE_PGID)). > > > > Oh, I naively assumed task_pgrp() would take an rcu lock... > > but it would not help ;)
Yeah, it doesn't do a get. :)
