Messages in this thread | | | Date | Tue, 29 Sep 2009 16:45:54 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] connector: Fix sid connector (was: Badness at kernel/softirq.c:143...) |
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On 09/29, Oleg Nesterov wrote: > > On 09/29, Evgeniy Polyakov wrote: > > > > On Tue, Sep 29, 2009 at 03:47:21PM +0200, Christian Borntraeger (borntraeger@de.ibm.com) wrote: > > > Ok, can confirm that this patch fixes my problem, but I am not sure if the > > > intended behaviour is still working as expected. > > > > Your patch breaks assumption that task_session(current->group_leader) is > > not equal to new session id, > > Afaics, no. > > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > @@ -1090,6 +1090,7 @@ SYSCALL_DEFINE0(setsid) > > struct pid *sid = task_pid(group_leader); > > pid_t session = pid_vnr(sid); > > int err = -EPERM; > > + int send_cn = 0; > > > > write_lock_irq(&tasklist_lock); > > /* Fail if I am already a session leader */ > > @@ -1104,12 +1105,18 @@ SYSCALL_DEFINE0(setsid) > > > > group_leader->signal->leader = 1; > > __set_special_pids(sid); > > + if (task_session(group_leader) != sid) > > + send_cn = 1; > > This is not right, task_session(group_leader) must be == sid after > __set_special_pids(). > > And I don't think "int send_cn" is needed. sys_setsid() must not > succeed if the caller lived in session == task_pid(group_leader).
IOW, if sys_setsid() succeeds, we know it creates the new unique session, we should report this change.
Note this check
if (pid_task(sid, PIDTYPE_PGID)) goto out;
before we actually change pids.
I think Christian's patch only needs the small fixup.
Oleg.
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