[PATCH v2] scsi: aic7xxx: aic79xx: add scb NULL check in ahd_handle_msg_reject()

[Aleksandr Aprelkov]

If ahd_get_scbptr() returns invalid scb_index then ahd_lookup_skb
returns NULL. Later in function scb used without check then NULL
pointer dereference can occur.

Add NULL scb check in else if statement so message gets rejected

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Aleksandr Aprelkov <aaprelkov@xxxxxxxxxxxx>
---
v2: Removed "!= 0" check as Damien Le Moal <dlemoal@xxxxxxxxxx>
suggested
 drivers/scsi/aic7xxx/aic79xx_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c
index 3e3100dbfda3..6bee62224d86 100644
--- a/drivers/scsi/aic7xxx/aic79xx_core.c
+++ b/drivers/scsi/aic7xxx/aic79xx_core.c
@@ -5577,7 +5577,7 @@ ahd_handle_msg_reject(struct ahd_softc *ahd, struct ahd_devinfo *devinfo)
 		       "Using asynchronous transfers\n",
 		       ahd_name(ahd), devinfo->channel,
 		       devinfo->target, devinfo->lun);
-	} else if ((scb->hscb->control & SIMPLE_QUEUE_TAG) != 0) {
+	} else if (scb && (scb->hscb->control & SIMPLE_QUEUE_TAG)) {
 		int tag_type;
 		int mask;
 
-- 
2.34.1