Re: [PATCH] scsi/virio_scsi.c: do not call virtscsi_remove_vqs() in virtscsi_init() to avoid crash bug

Stefan Hajnoczi
2018-10-12T14:55:50Z

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On Thu, Aug 23, 2018 at 10:24:58AM +0800, piaojun wrote:
> If some error happened before find_vqs, error branch will goto
> virtscsi_remove_vqs to free vqs. Actually the vqs have not been allocated
> successfully, so this will cause wild-pointer-free problem. So
> virtscsi_remove_vqs could be deleted as no error will happen after
> find_vqs.
>
> Signed-off-by: Jun Piao <piaojun@huawei.com>
> ---
> drivers/scsi/virtio_scsi.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 1c72db9..da0fd74 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -833,8 +833,6 @@ static int virtscsi_init(struct virtio_device *vdev,
> kfree(names);
> kfree(callbacks);
> kfree(vqs);
> - if (err)
> - virtscsi_remove_vqs(vdev);

Can you provide more details about the problem?

drivers/virtio/virtio_pci_common.c:vp_del_vqs() looks fine to me, it
iterates over vdev->vqs. The vdev->vqs list has been initialized in
drivers/virtio/virtio.c:register_virtio_device() and it's empty.

Stefan

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