scsi: pm8001: Fix use-after-free for aborted TMF sas_task

Currently a use-after-free may occur if a TMF sas_task is aborted before we
handle the IO completion in mpi_ssp_completion(). The abort occurs due to
timeout.

When the timeout occurs, the SAS_TASK_STATE_ABORTED flag is set and the
sas_task is freed in pm8001_exec_internal_tmf_task().

However, if the I/O completion occurs later, the I/O completion still
thinks that the sas_task is available. Fix this by clearing the ccb->task
if the TMF times out - the I/O completion handler does nothing if this
pointer is cleared.

Link: https://lore.kernel.org/r/1643289172-165636-3-git-send-email-john.garry@huawei.com


Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>