On 04/04, [email protected] wrote: > > v2: slight clarification in comments, put the conditional around the > whole wakeup area
Acked-by: Oleg Nesterov <[email protected]> and I think this should go to -stable. > Oleg mentioned a preference for making LISTEN unfreeze instead; I have > no preference there, Yes, but I won't insist if you prefer this more simple fix, > just wanted to make sure that this doesn't get > forgotten entirely. And you are right, I forgot about this bug. Thanks! Oleg. > kernel/ptrace.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > index 0af928712174..7cc49c3e73af 100644 > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -184,11 +184,17 @@ static void ptrace_unfreeze_traced(struct task_struct > *task) > > WARN_ON(!task->ptrace || task->parent != current); > > + /* > + * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up > + * remotely. Recheck state under the lock to close this race. > + */ > spin_lock_irq(&task->sighand->siglock); > - if (__fatal_signal_pending(task)) > - wake_up_state(task, __TASK_TRACED); > - else > - task->state = TASK_TRACED; > + if (task->state == __TASK_TRACED) { > + if (__fatal_signal_pending(task)) > + wake_up_state(task, __TASK_TRACED); > + else > + task->state = TASK_TRACED; > + } > spin_unlock_irq(&task->sighand->siglock); > } > > -- > 2.12.2.715.g7642488e1d-goog >
