diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index c884858..388440e 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -569,7 +569,7 @@
 
 #ifdef HAVE_PCI_MMAP
 
-static int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vma)
+int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vma)
 {
 	unsigned long nr, start, size;
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 9de87e9..d3e65e2 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -10,6 +10,10 @@
 extern int pci_create_sysfs_dev_files(struct pci_dev *pdev);
 extern void pci_remove_sysfs_dev_files(struct pci_dev *pdev);
 extern void pci_cleanup_rom(struct pci_dev *dev);
+#ifdef HAVE_PCI_MMAP
+extern int pci_mmap_fits(struct pci_dev *pdev, int resno,
+			 struct vm_area_struct *vma);
+#endif
 
 /**
  * Firmware PM callbacks
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index e1098c3..7fb086d 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -252,11 +252,20 @@
 	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(dev, i, vma))
+			break;
+	}
+
+	if (i >= PCI_ROM_RESOURCE)
+		return -ENODEV;
+
 	ret = pci_mmap_page_range(dev, vma,
 				  fpriv->mmap_state,
 				  fpriv->write_combine);