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    SubjectRe: [patch 1/3 v2] vfio: signedness bug in vfio_config_do_rw()
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    On Thu, 2012-06-28 at 11:07 +0300, Dan Carpenter wrote:
    > The "count" variable needs to be signed here because we use it to store
    > negative error codes.
    >
    > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
    > ---
    > v2: Just declare count as signed.
    >
    > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
    > index a4f7321..2e00aa8 100644
    > --- a/drivers/vfio/pci/vfio_pci_config.c
    > +++ b/drivers/vfio/pci/vfio_pci_config.c
    > @@ -1419,7 +1419,7 @@ void vfio_config_free(struct vfio_pci_device *vdev)
    > }
    >
    > static ssize_t vfio_config_do_rw(struct vfio_pci_device *vdev, char __user *buf,
    > - size_t count, loff_t *ppos, bool iswrite)
    > + ssize_t count, loff_t *ppos, bool iswrite)
    > {
    > struct pci_dev *pdev = vdev->pdev;
    > struct perm_bits *perm;

    signed doesn't seem right for count since just below this chunk we do:

    if (*ppos < 0 || *ppos + count > pdev->cfg_size)
    return -EFAULT;

    So then we have to start testing for negative count. I've added a
    ssize_t variable for return that should clear things up. Thanks for the
    report!

    Alex



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