diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index e1098c3..d1ea256 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -252,11 +252,20 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
 	const struct proc_dir_entry *dp = PDE(inode);
 	struct pci_dev *dev = dp->data;
 	struct pci_filp_private *fpriv = file->private_data;
-	int ret;
+	int i, ret;
 
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
 
+	/* Make sure the caller is mapping a real resource for this device */
+	for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+		if (pci_mmap_fits(pdev, i, vma))
+			break;
+	}
+
+	if (i >= PCI_ROM_RESOURCE)
+		return -ENODEV;
+
 	ret = pci_mmap_page_range(dev, vma,
 				  fpriv->mmap_state,
 				  fpriv->write_combine);