[PATCH net v3 3/9] ibmvnic: avoid memset null scrq msgs

[Dany Madden <drt@linux.ibm.com>]

scrq->msgs could be NULL during device reset, causing Linux to crash.
So, check before memset scrq->msgs.

Fixes: c8b2ad0a4a901 ("ibmvnic: Sanitize entire SCRQ buffer on reset")
Signed-off-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index d5a927bb4954..b08f95017825 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2845,15 +2845,26 @@ static int reset_one_sub_crq_queue(struct ibmvnic_adapter *adapter,
 {
 	int rc;
 
+	if (!scrq) {
+		netdev_dbg(adapter->netdev,
+			   "Invalid scrq reset. irq (%d) or msgs (%p).\n",
+			   scrq->irq, scrq->msgs);
+		return -EINVAL;
+	}
+
 	if (scrq->irq) {
 		free_irq(scrq->irq, scrq);
 		irq_dispose_mapping(scrq->irq);
 		scrq->irq = 0;
 	}
-
-	memset(scrq->msgs, 0, 4 * PAGE_SIZE);
-	atomic_set(&scrq->used, 0);
-	scrq->cur = 0;
+	if (scrq->msgs) {
+		memset(scrq->msgs, 0, 4 * PAGE_SIZE);
+		atomic_set(&scrq->used, 0);
+		scrq->cur = 0;
+	} else {
+		netdev_dbg(adapter->netdev, "Invalid scrq reset\n");
+		return -EINVAL;
+	}
 
 	rc = h_reg_sub_crq(adapter->vdev->unit_address, scrq->msg_token,
 			   4 * PAGE_SIZE, &scrq->crq_num, &scrq->hw_irq);
-- 
2.26.2