* Re: [PATCH v2] scsi: virtio_scsi: Fix poential NULL pointer dereference in virtscsi_rescan_hotunplug
[not found] <20230202064124.22277-1-zyytlz.wz@163.com>
@ 2023-02-13 12:09 ` Michael S. Tsirkin
2023-02-14 16:41 ` Stefan Hajnoczi
0 siblings, 1 reply; 2+ messages in thread
From: Michael S. Tsirkin @ 2023-02-13 12:09 UTC (permalink / raw)
To: Zheng Wang
Cc: alex000young, security, linux-scsi, martin.petersen, linux-kernel,
hackerzheng666, virtualization, stefanha, pbonzini, jejb
On Thu, Feb 02, 2023 at 02:41:24PM +0800, Zheng Wang wrote:
> 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>
> ---
I fixed a typo in subject and tweaked the patch a bit
> 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;
>
dropped = 0 here
> if (event->event &
> cpu_to_virtio32(vscsi->vdev, VIRTIO_SCSI_T_EVENTS_MISSED)) {
and moved declaration here.
> 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
>
>
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