lkml.org 
[lkml]   [2011]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] ptrace: use safer wake up on ptrace_detach()
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);
>


\
 
 \ /
  Last update: 2011-02-02 01:31    [from the cache]
©2003-2011 Jasper Spaans