Patch "PCI: Only allow WC mmap on prefetchable resources" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

PCI: Only allow WC mmap on prefetchable resources

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pci-only-allow-wc-mmap-on-prefetchable-resources.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Woodhouse <[email protected]>
Date: Wed, 12 Apr 2017 13:25:52 +0100
Subject: PCI: Only allow WC mmap on prefetchable resources

From: David Woodhouse <[email protected]>

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.

---
 drivers/pci/proc.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

@@ -231,7 +231,7 @@ static int proc_bus_pci_mmap(struct file
 {
 	struct pci_dev *dev = PDE_DATA(file_inode(file));
 	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;

@@ -251,10 +251,13 @@ 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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/pci-fix-another-sanity-check-bug-in-proc-pci-mmap.patch queue-4.9/pci-only-allow-wc-mmap-on-prefetchable-resources.patch queue-4.9/pci-fix-pci_mmap_fits-for-have_pci_resource_to_user-platforms.patch queue-4.9/iommu-vt-d-flush-the-iotlb-to-get-rid-of-the-initial-kdump-mappings.patch