| From: David Woodhouse <dwmw@amazon.co.uk> |
| Date: Wed, 12 Apr 2017 13:25:52 +0100 |
| Subject: PCI: Only allow WC mmap on prefetchable resources |
| |
| commit cef4d02305a06be581bb7f4353446717a1b319ec upstream. |
| |
| The /proc/bus/pci mmap interface allows the user to specify whether they |
| want WC or not. Don't let them do so on non-prefetchable BARs. |
| |
| Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> |
| Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| drivers/pci/proc.c | 13 ++++++++----- |
| 1 file changed, 8 insertions(+), 5 deletions(-) |
| |
| --- a/drivers/pci/proc.c |
| +++ b/drivers/pci/proc.c |
| @@ -249,7 +249,7 @@ static int proc_bus_pci_mmap(struct file |
| const struct proc_dir_entry *dp = PDE(inode); |
| struct pci_dev *dev = dp->data; |
| struct pci_filp_private *fpriv = file->private_data; |
| - int i, ret, write_combine, res_bit; |
| + int i, ret, write_combine = 0, res_bit; |
| |
| if (!capable(CAP_SYS_RAWIO)) |
| return -EPERM; |
| @@ -269,10 +269,13 @@ static int proc_bus_pci_mmap(struct file |
| if (i >= PCI_ROM_RESOURCE) |
| return -ENODEV; |
| |
| - if (fpriv->mmap_state == pci_mmap_mem) |
| - write_combine = fpriv->write_combine; |
| - else |
| - write_combine = 0; |
| + if (fpriv->mmap_state == pci_mmap_mem && |
| + fpriv->write_combine) { |
| + if (dev->resource[i].flags & IORESOURCE_PREFETCH) |
| + write_combine = 1; |
| + else |
| + return -EINVAL; |
| + } |
| ret = pci_mmap_page_range(dev, vma, |
| fpriv->mmap_state, write_combine); |
| if (ret < 0) |
