Messages in this thread | | | Date | Fri, 1 Sep 2006 00:49:20 -0700 | From | Andrew Morton <> | Subject | Re: Trouble with ptrace self-attach rule since kernel > 2.6.14 |
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On Fri, 1 Sep 2006 09:36:38 +0200 Andreas Hobein <ah2@delair.de> wrote:
> On Friday 01 September 2006 03:39, Andrew Morton wrote: > > I'm unable to identify what patch you're referring to here. Please be more > > specific so we can ask the person who developed it. > > I assume the attached patch from Linus Torvalds causes my problem, since the > condition was changed from "if (task == current)" to "if (task->tgid == > current->tgid)" it breaks my application code. There may be other parts of > the ptrace() kernel code that where changed accordingly that I'm not aware. > > There is also a reply from Roland McGrath (see > http://lkml.org/lkml/2005/11/9/460) who mentioned that there may occur some > problems in "some real programs out there". May be I'm the first one who is > affected by this new behaviour.
When you have names, please cc them..
> To summarise my questions: > - Why should a thread not be allowed to ptrace_attach to a sibling thread > - while a forked child of this thread may do this ? > - Is there any other way to suspend sibling threads at arbitrary points like > phread_suspend_np() does for example on AIX? > > Thanks, Andreas > > --------------------------- > >From torvalds@osdl.org Wed Nov 9 12:04:07 2005 > Date: Wed, 9 Nov 2005 11:37:57 -0800 (PST) > From: Linus Torvalds <torvalds@osdl.org> > Subject: Fix ptrace self-attach rule > > Before we did CLONE_THREAD, the way to check whether we were attaching > to ourselves was to just check "current == task", but with CLONE_THREAD > we should check that the thread group ID matches instead. > > Signed-off-by: Linus Torvalds <torvalds@osdl.org> > --- > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > index 5b8dd98..b88d418 100644 > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -155,7 +155,7 @@ int ptrace_attach(struct task_struct *ta > retval = -EPERM; > if (task->pid <= 1) > goto bad; > - if (task == current) > + if (task->tgid == current->tgid) > goto bad; > /* the same process cannot be attached many times */ > if (task->ptrace & PT_PTRACED) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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