scsi: hisi_sas: Fix NULL pointer dereference

There is a NULL pointer dereference in case *slot* happens to be NULL at
lines 1053 and 1878:

struct hisi_sas_cq *cq =
	&hisi_hba->cq[slot->dlvry_queue];

Notice that *slot* is being NULL checked at lines 1057 and 1881:
if (slot), which implies it may be NULL.

Fix this by placing the declaration and definition of variable cq, which
contains the pointer dereference slot->dlvry_queue, after slot has been
properly NULL checked.

Addresses-Coverity-ID: 1474515 ("Dereference before null check")
Addresses-Coverity-ID: 1474520 ("Dereference before null check")
Fixes: 584f53fe5f52 ("scsi: hisi_sas: Fix the race between IO completion and timeout for SMP/internal IO")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 2e5eaf1..b3f01d5 100644 (file)
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -1050,11 +1050,11 @@ static int hisi_sas_exec_internal_tmf_task(struct domain_device *device,
                if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
                        if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
                                struct hisi_sas_slot *slot = task->lldd_task;
-                               struct hisi_sas_cq *cq =
-                                       &hisi_hba->cq[slot->dlvry_queue];
 
                                dev_err(dev, "abort tmf: TMF task timeout and not done\n");
                                if (slot) {
+                                       struct hisi_sas_cq *cq =
+                                              &hisi_hba->cq[slot->dlvry_queue];
                                        /*
                                         * flush tasklet to avoid free'ing task
                                         * before using task in IO completion
@@ -1875,10 +1875,10 @@ hisi_sas_internal_task_abort(struct hisi_hba *hisi_hba,
        if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
                if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
                        struct hisi_sas_slot *slot = task->lldd_task;
-                       struct hisi_sas_cq *cq =
-                               &hisi_hba->cq[slot->dlvry_queue];
 
                        if (slot) {
+                               struct hisi_sas_cq *cq =
+                                       &hisi_hba->cq[slot->dlvry_queue];
                                /*
                                 * flush tasklet to avoid free'ing task
                                 * before using task in IO completion