Messages in this thread | | | Date | Tue, 1 Feb 2011 16:27:29 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] ptrace: use safer wake up on ptrace_detach() |
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On Tue, 1 Feb 2011 11:26:18 +0100 Tejun Heo <tj@kernel.org> wrote:
> The wake_up_process() call in ptrace_detach() is spurious and not > interlocked with the tracee state. IOW, the tracee could be running > or sleeping in any place in the kernel by the time wake_up_process() > is called. This can lead to the tracee waking up unexpectedly which > can be dangerous. > > The wake_up is spurious and should be removed but for now reduce its > toxicity by only waking up if the tracee is in TRACED or STOPPED > state. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Cc: Roland McGrath <roland@redhat.com> > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: stable@kernel.org
Am unable to work out why you tagged it for backporting. It fixes some observed bug? Perhaps a regression?
> Index: work/kernel/ptrace.c > =================================================================== > --- work.orig/kernel/ptrace.c > +++ work/kernel/ptrace.c > @@ -313,7 +313,7 @@ int ptrace_detach(struct task_struct *ch > child->exit_code = data; > dead = __ptrace_detach(current, child); > if (!child->exit_state) > - wake_up_process(child); > + wake_up_state(child, TASK_TRACED | TASK_STOPPED); > } > write_unlock_irq(&tasklist_lock); >
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