From:   Zheng Wang <zyytlz.wz@163.com>
To:     mst@redhat.com
Cc:     hackerzheng666@gmail.com, jasowang@redhat.com, pbonzini@redhat.com,
        stefanha@redhat.com, jejb@linux.ibm.com,
        martin.petersen@oracle.com,
        virtualization@lists.linux-foundation.org,
        linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        security@kernel.org, alex000young@gmail.com,
        Zheng Wang <zyytlz.wz@163.com>
Subject: [PATCH v2] scsi: virtio_scsi: Fix poential NULL pointer dereference in  virtscsi_rescan_hotunplug
Date:   Thu,  2 Feb 2023 14:41:24 +0800
Message-Id: <20230202064124.22277-1-zyytlz.wz@163.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@163.com>
---
v2:
- add kfree to avoid memory leak
---
 drivers/scsi/virtio_scsi.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index d07d24c06b54..a66d8815d738 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -330,7 +330,7 @@ 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);
@@ -338,6 +338,11 @@ static void virtscsi_rescan_hotunplug(struct virtio_scsi *vscsi)
 	int result, inquiry_len, inq_result_len = 256;
 	char *inq_result = kmalloc(inq_result_len, GFP_KERNEL);
 
+	if (!inq_result) {
+		kfree(inq_result);
+		return -ENOMEM;
+	}
+
 	shost_for_each_device(sdev, shost) {
 		inquiry_len = sdev->inquiry_len ? sdev->inquiry_len : 36;
 
@@ -366,6 +371,7 @@ 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 +380,15 @@ 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