Commit b90cd6f2 authored by Jason Yan's avatar Jason Yan Committed by Martin K. Petersen

scsi: libsas: fix a race condition when smp task timeout

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(). Once the
LLDD sets DONE, it must call task->done(), which will call
smp_task_done()->complete() and the task will be completed and freed
correctly.
Reported-by: default avatarchenxiang <chenxiang66@hisilicon.com>
Signed-off-by: default avatarJason Yan <yanaijie@huawei.com>
CC: John Garry <john.garry@huawei.com>
CC: Johannes Thumshirn <jthumshirn@suse.de>
CC: Ewan Milne <emilne@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Tomas Henzl <thenzl@redhat.com>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Hannes Reinecke <hare@suse.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarJohn Garry <john.garry@huawei.com>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 437207d3
...@@ -48,17 +48,16 @@ static void smp_task_timedout(struct timer_list *t) ...@@ -48,17 +48,16 @@ static void smp_task_timedout(struct timer_list *t)
unsigned long flags; unsigned long flags;
spin_lock_irqsave(&task->task_state_lock, 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; task->task_state_flags |= SAS_TASK_STATE_ABORTED;
complete(&task->slow_task->completion);
}
spin_unlock_irqrestore(&task->task_state_lock, flags); spin_unlock_irqrestore(&task->task_state_lock, flags);
complete(&task->slow_task->completion);
} }
static void smp_task_done(struct sas_task *task) static void smp_task_done(struct sas_task *task)
{ {
if (!del_timer(&task->slow_task->timer)) del_timer(&task->slow_task->timer);
return;
complete(&task->slow_task->completion); complete(&task->slow_task->completion);
} }
......
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