linux-kernel - Re: [PATCH 1/3] ptrace: ptrace_attach: check PF_KTHREAD + exit

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Date:	Tue, 5 May 2009 18:24:44 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	chrisw@...s-sol.org, roland@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] ptrace: ptrace_attach: check PF_KTHREAD +
 exit_state instead of ->mm

On Wed, 6 May 2009 01:57:36 +0200 Oleg Nesterov <oleg@...hat.com> wrote:

> On 05/05, Andrew Morton wrote:
> >
> > On Wed, 6 May 2009 00:47:22 +0200
> > Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > > - Add PF_KTHREAD check to prevent attaching to the kernel thread
> > >   with a borrowed ->mm.
> > >
> > >   With or without this change we can race with daemonize() which
> > >   can set PF_KTHREAD or clear ->mm after ptrace_attach() does the
> > >   check, but this doesn't matter because reparent_to_kthreadd()
> > >   does ptrace_unlink().
> > >
> > > - Kill "!task->mm" check. We don't really care about ->mm != NULL,
> > >   and the task can call exit_mm() right after we drop task_lock().
> > >   What we need is to make sure we can't attach after exit_notify(),
> > >   check task->exit_state != 0 instead.
> > >
> >
> > These patches make a mess of utrace-core.patch.  Do we really want to do that?
> 
> Aaaah. Sorry! forgot to clearify...
> 
> These patches depend on
> 
> 	utrace-core-kill-exclude_xtrace-logic.patch
> 
> which hopefully can be folded into utrace-core.patch. In that case these
> changes do not depend on utrace, and they can go ahead of utrace.
> 

oic.  Strange that the patches applied, but utrace didn't apply on them.

I now have:

#
# ptrace
#
ptrace-remove-pt_dtrace-from-arch-h8300.patch
ptrace-remove-pt_dtrace-from-avr32-mn10300-parisc-s390-sh-xtensa.patch
ptrace-remove-pt_dtrace-from-m68k-m68knommu.patch
ptrace-remove-pt_dtrace-from-arch-m32r.patch
ptrace-mm_need_new_owner-use-real_parent-to-search-in-the-siblings.patch
ptrace-tracehook_unsafe_exec-remove-the-stale-comment.patch
ptrace-tracehook_unsafe_exec-remove-the-stale-comment-fix.patch
ptrace-do-not-use-task-ptrace-directly-in-core-kernel.patch
#
# utrace
#
signals-tracehook_notify_jctl-change.patch
utrace-core.patch
utrace-core-kill-exclude_xtrace-logic.patch
#
ptrace-ptrace_attach-check-pf_kthread-exit_state-instead-of-mm.patch
ptrace-cleanup-check-set-of-pt_ptraced-during-attach.patch
ptrace-do-not-use-task_lock-for-attach.patch
ptrace_get_task_struct-s-tasklist-rcu-make-it-static.patch

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