scsi: pm8001: Fix use-after-free for aborted SSP/STP sas_task

Currently a use-after-free may occur if a sas_task is aborted by the upper
layer before we handle the I/O completion in mpi_ssp_completion() or
mpi_sata_completion().

In this case, the following are the two steps in handling those I/O
completions:

 - Call complete() to inform the upper layer handler of completion of
   the I/O.

 - Release driver resources associated with the sas_task in
   pm8001_ccb_task_free() call.

When complete() is called, the upper layer may free the sas_task. As such,
we should not touch the associated sas_task afterwards, but we do so in the
pm8001_ccb_task_free() call.

Fix by swapping the complete() and pm8001_ccb_task_free() calls ordering.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Damien Le Moal <[email protected]>
Acked-by: Jack Wang <[email protected]>
Signed-off-by: John Garry <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

diff --git a/drivers/scsi/pm8001/pm80xx_hwi.c b/drivers/scsi/pm8001/pm80xx_hwi.c
index b7ab643ef014ed50fd31b6c7fd63fcdbe6438c2e..9d20f8009b89fca081401bb98123d1828b338c6d 100644 (file)
--- a/drivers/scsi/pm8001/pm80xx_hwi.c
+++ b/drivers/scsi/pm8001/pm80xx_hwi.c
@@ -2185,9 +2185,9 @@ mpi_ssp_completion(struct pm8001_hba_info *pm8001_ha, void *piomb)
                pm8001_dbg(pm8001_ha, FAIL,
                           "task 0x%p done with io_status 0x%x resp 0x%x stat 0x%x but aborted by upper layer!\n",
                           t, status, ts->resp, ts->stat);
+               pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
                if (t->slow_task)
                        complete(&t->slow_task->completion);
-               pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
        } else {
                spin_unlock_irqrestore(&t->task_state_lock, flags);
                pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
@@ -2794,9 +2794,9 @@ mpi_sata_completion(struct pm8001_hba_info *pm8001_ha,
                pm8001_dbg(pm8001_ha, FAIL,
                           "task 0x%p done with io_status 0x%x resp 0x%x stat 0x%x but aborted by upper layer!\n",
                           t, status, ts->resp, ts->stat);
+               pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
                if (t->slow_task)
                        complete(&t->slow_task->completion);
-               pm8001_ccb_task_free(pm8001_ha, t, ccb, tag);
        } else {
                spin_unlock_irqrestore(&t->task_state_lock, flags);
                spin_unlock_irqrestore(&circularQ->oq_lock,