linux-kernel - Re: [PATCH 04/20] virtio: Implement get_shm

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Date:   Tue, 10 Mar 2020 14:47:20 -0400
From:   Vivek Goyal <vgoyal@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, virtio-fs@...hat.com, miklos@...redi.hu,
        stefanha@...hat.com, dgilbert@...hat.com,
        Sebastien Boeuf <sebastien.boeuf@...el.com>,
        kbuild test robot <lkp@...el.com>
Subject: Re: [PATCH 04/20] virtio: Implement get_shm_region for PCI transport

On Tue, Mar 10, 2020 at 07:12:25AM -0400, Michael S. Tsirkin wrote:
[..]
> > +static bool vp_get_shm_region(struct virtio_device *vdev,
> > +			      struct virtio_shm_region *region, u8 id)
> > +{
> > +	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > +	struct pci_dev *pci_dev = vp_dev->pci_dev;
> > +	u8 bar;
> > +	u64 offset, len;
> > +	phys_addr_t phys_addr;
> > +	size_t bar_len;
> > +	int ret;
> > +
> > +	if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len)) {
> > +		return false;
> > +	}
> > +
> > +	ret = pci_request_region(pci_dev, bar, "virtio-pci-shm");
> > +	if (ret < 0) {
> > +		dev_err(&pci_dev->dev, "%s: failed to request BAR\n",
> > +			__func__);
> > +		return false;
> > +	}
> > +
> > +	phys_addr = pci_resource_start(pci_dev, bar);
> > +	bar_len = pci_resource_len(pci_dev, bar);
> > +
> > +        if (offset + len > bar_len) {
> > +                dev_err(&pci_dev->dev,
> > +                        "%s: bar shorter than cap offset+len\n",
> > +                        __func__);
> > +                return false;
> > +        }
> > +
> 
> Something wrong with indentation here.

Will fix all indentation related issues in this patch.

> Also as long as you are validating things, it's worth checking
> offset + len does not overflow.

Something like addition of following lines?

+       if ((offset + len) < offset) {
+               dev_err(&pci_dev->dev, "%s: cap offset+len overflow detected\n",
+                       __func__);
+               return false;
+       }

Vivek