Re: [PATCH 2/3] posix_timer: fix error path in timer_create

From: Stanislaw Gruszka
Date: Mon May 17 2010 - 10:29:57 EST


On Mon, 17 May 2010 17:41:43 +0400
Andrey Vagin <avagin@xxxxxxxxxx> wrote:

> move CLOCK_DISPATCH(which_clock, timer_create, (new_timer)) after all
> possible EFAULT errors.
>
> *_timer_create may allocate/get resources.
> (for example posix_cpu_timer_create does get_task_struct)
>
> Signed-off-by: Andrey Vagin <avagin@xxxxxxxxxx>
> ---
> kernel/posix-timers.c | 16 ++++++++--------
> 1 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
> index 5555e7c..8393624 100644
> --- a/kernel/posix-timers.c
> +++ b/kernel/posix-timers.c
> @@ -555,14 +555,6 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
> goto out;
> }
>
> - it_id_set = IT_ID_SET;
> - new_timer->it_id = (timer_t) new_timer_id;
> - new_timer->it_clock = which_clock;
> - new_timer->it_overrun = -1;
> - error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
> - if (error)
> - goto out;
> -
> if (copy_to_user(created_timer_id,
> &new_timer_id, sizeof (new_timer_id))) {
> error = -EFAULT;
> @@ -593,6 +585,14 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
> new_timer->sigq->info.si_tid = new_timer->it_id;
> new_timer->sigq->info.si_code = SI_TIMER;
>
> + it_id_set = IT_ID_SET;
> + new_timer->it_id = (timer_t) new_timer_id;

This part should not be moved, this make possible leak of idr entry .

> + new_timer->it_clock = which_clock;
> + new_timer->it_overrun = -1;

I'm not so convenient of moving this as well.

> + error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer));
> + if (error)
> + goto out;
> +
> spin_lock_irq(&current->sighand->siglock);
> new_timer->it_signal = current->signal;
> list_add(&new_timer->list, &current->signal->posix_timers);

Thanks
Stanislaw
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