Messages in this thread | | | Date | Tue, 21 Nov 2006 17:02:28 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH -mm 3/4][AIO] - AIO completion signal notification |
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On Mon, 20 Nov 2006 15:22:52 +0100 S__bastien Dugu__ <sebastien.dugue@bull.net> wrote:
> +static long aio_setup_sigevent(struct aio_notify *notify, > + struct sigevent __user *user_event) > +{ > + sigevent_t event; > + struct task_struct *target; > + > + if (copy_from_user(&event, user_event, sizeof (event))) > + return -EFAULT; > + > + if (event.sigev_notify == SIGEV_NONE) > + return 0; > + > + notify->notify = event.sigev_notify; > + notify->signo = event.sigev_signo; > + notify->value = event.sigev_value; > + > + read_lock(&tasklist_lock); > + target = good_sigevent(&event); > + > + if (unlikely(!target || (target->flags & PF_EXITING))) > + goto out_unlock; > + > + notify->target = target; > + > + if (notify->notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) { > + /* > + * This reference will be dropped in really_put_req() when > + * we're done with the request. > + */ > + get_task_struct(target); > + }
It worries me that this function can save away a task_struct* without having taken a reference against it.
> + read_unlock(&tasklist_lock); > + > + /* > + * NOTE: we cannot free the sigqueue in the completion path as > + * the signal may not have been delivered to the target task. > + * Therefore it has to be freed in __sigqueue_free() when the > + * signal is collected if si_code is SI_ASYNCIO. > + */ > + notify->sigq = sigqueue_alloc(); > + > + if (unlikely(!notify->sigq)) > + return -EAGAIN; > + > + return 0; > + > +out_unlock: > + read_unlock(&tasklist_lock); > + return -EINVAL; > +} - 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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