Prev: input: mt: Document the MT event slot protocol (rev3)
Next: [PATCH -mm 1/1] ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm
From: Oleg Nesterov on 22 May 2010 11:00
On 05/21, Roland McGrath wrote:
>
> > This looks unsafe. What protect child->mm if ptrace() races with SIGKILL ?
> >
> > Of course, I do not blame this patch, the code was copied from arch/, but
> > I think we need another patch which checks ->mm != NULL under task_lock()
> > on top of this one?
>
> Agreed, unless things are somehow different on nommu so there aren't such
> races.

I don't this !CONFG_MMU can make any difference, nothing can protect us
from exit_mm() afaics.

> But, as you mention, this is a long-standing issue that is entirely
> unrelated to the cleanup here and should not delay merging this patch.

Yes, yes, agreed.

Please see the patch on top of ptrace-unify-fdpic-implementations.patch
Untested, but hopefully trivial enough.

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: input: mt: Document the MT event slot protocol (rev3)
Next: [PATCH -mm 1/1] ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm