[PATCH] NULL check in twl_scsiop_execute_scsi()

[Alexander Sapozhnikov <alsp705@gmail.com>]

From: Alexandr Sapozhnikov <alsp705@gmail.com>

After having been compared to NULL value at 3w-sas.c:322, 
pointer 'srb' is passed as 1st parameter in call to 
function 'scsi_sg_count' at 3w-sas.c:336, where it is dereferenced.

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

Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
---
 drivers/scsi/3w-sas.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/3w-sas.c b/drivers/scsi/3w-sas.c
index 3ebe661..674c130 100644
--- a/drivers/scsi/3w-sas.c
+++ b/drivers/scsi/3w-sas.c
@@ -333,7 +333,7 @@ static int twl_scsiop_execute_scsi(TW_Device_Extension *tw_dev, int request_id,
 
 	if (!sglistarg) {
 		/* Map sglist from scsi layer to cmd packet */
-		if (scsi_sg_count(srb)) {
+		if (srb && scsi_sg_count(srb)) {
 			sg_count = scsi_dma_map(srb);
 			if (sg_count <= 0)
 				goto out;
-- 
2.5.3