On 09/12/2018 10:29 AM, Jason Yan wrote:
> When the lldd is processing the complete sas task in interrupt and set
> the task stat as SAS_TASK_STATE_DONE, the smp timeout timer is able to
> be triggered at the same time. And smp_task_timedout() will complete the
> task wheter the SAS_TASK_STATE_DONE is set or not. Then the sas task may
> freed before lldd end the interrupt process. Thus a use-after-free will
> happen.
>
> Fix this by calling the complete() only when SAS_TASK_STATE_DONE is not
> set. And remove the check of the return value of the del_timer().
>
> Reported-by: chenxiang <chenxiang66@xxxxxxxxxxxxx>
> Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
> CC: John Garry <john.garry@xxxxxxxxxx>
> CC: Johannes Thumshirn <jthumshirn@xxxxxxx>
> CC: Ewan Milne <emilne@xxxxxxxxxx>
> CC: Christoph Hellwig <hch@xxxxxx>
> CC: Tomas Henzl <thenzl@xxxxxxxxxx>
> CC: Dan Williams <dan.j.williams@xxxxxxxxx>
> CC: Hannes Reinecke <hare@xxxxxxxx>
> ---
> drivers/scsi/libsas/sas_expander.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 52222940d398..0d1f72752ca2 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -48,17 +48,16 @@ static void smp_task_timedout(struct timer_list *t)
> unsigned long flags;
>
> spin_lock_irqsave(&task->task_state_lock, flags);
> - if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
> + if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
> task->task_state_flags |= SAS_TASK_STATE_ABORTED;
> + complete(&task->slow_task->completion);
> + }
> spin_unlock_irqrestore(&task->task_state_lock, flags);
> -
> - complete(&task->slow_task->completion);
> }
>
> static void smp_task_done(struct sas_task *task)
> {
> - if (!del_timer(&task->slow_task->timer))
> - return;
> + del_timer(&task->slow_task->timer);
> complete(&task->slow_task->completion);
> }
>
>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Cheers,
Hannes
