On 12/09/2018 09:29, 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().
Hi Jason,
Please mention that once the LLDD sets DONE, it must call task->done(),
which will call smp_task_done()->complete()
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);
Nit: for consistency with any other time we use this lock, can we call
complete() outside the lock? Maybe just use a flag variable for this.
+ }
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);
}
Do we also need this change or similar:
static int smp_execute_task_sg(struct domain_device *dev,
if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
SAS_DPRINTK("smp task timed out or aborted\n");
i->dft->lldd_abort_task(task);
- if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
- SAS_DPRINTK("SMP task aborted and not done\n");
- break;
- }
+ break;
To me, the ABORTED and DONE states are mutually exclusive.
Thanks,
John
