[PATCH] scsi: virtio_scsi: Fix poential NULL pointer dereference in virtscsi_rescan_hotunplug

[Zheng Wang]

There is no check about the return value of kmalloc in 
virtscsi_rescan_hotunplug. Add the check to avoid use 
of null pointer 'inq_result' in case of the failure
of kmalloc.

Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
---
 drivers/scsi/virtio_scsi.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index d07d24c06b54..f198e281b1d3 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -330,13 +330,16 @@ static void virtscsi_handle_param_change(struct virtio_scsi *vscsi,
 	scsi_device_put(sdev);
 }
 
-static void virtscsi_rescan_hotunplug(struct virtio_scsi *vscsi)
+static int virtscsi_rescan_hotunplug(struct virtio_scsi *vscsi)
 {
 	struct scsi_device *sdev;
 	struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
 	unsigned char scsi_cmd[MAX_COMMAND_SIZE];
 	int result, inquiry_len, inq_result_len = 256;
 	char *inq_result = kmalloc(inq_result_len, GFP_KERNEL);
+
+	if (!inq_result)
+		return -ENOMEM;
 
 	shost_for_each_device(sdev, shost) {
 		inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
@@ -366,6 +369,7 @@ static void virtscsi_rescan_hotunplug(struct virtio_scsi *vscsi)
 	}
 
 	kfree(inq_result);
+	return 0;
 }
 
 static void virtscsi_handle_event(struct work_struct *work)
@@ -374,12 +378,15 @@ static void virtscsi_handle_event(struct work_struct *work)
 		container_of(work, struct virtio_scsi_event_node, work);
 	struct virtio_scsi *vscsi = event_node->vscsi;
 	struct virtio_scsi_event *event = &event_node->event;
+	int ret = 0;
 
 	if (event->event &
 	    cpu_to_virtio32(vscsi->vdev, VIRTIO_SCSI_T_EVENTS_MISSED)) {
 		event->event &= ~cpu_to_virtio32(vscsi->vdev,
 						   VIRTIO_SCSI_T_EVENTS_MISSED);
-		virtscsi_rescan_hotunplug(vscsi);
+		ret = virtscsi_rescan_hotunplug(vscsi);
+		if (ret)
+			return;
 		scsi_scan_host(virtio_scsi_host(vscsi->vdev));
 	}
 
-- 
2.25.1