From: David Woodhouse Date: Wed, 12 Apr 2017 12:25:52 +0000 (+0100) Subject: PCI: Only allow WC mmap on prefetchable resources X-Git-Tag: v4.12-rc1~65^2~2^2~19 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=cef4d02305a06be581bb7f4353446717a1b319ec;p=karo-tx-linux.git PCI: Only allow WC mmap on prefetchable resources 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 Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org --- diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index 62a0c3e788d3..dc8912e2d4a1 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -231,7 +231,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma) { 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 *file, struct vm_area_struct *vma) 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)