ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order

According to the changelog of commit 29ed1f29b68a (PCI: pciehp: Fix null
pointer deref when hot-removing SR-IOV device) it is unsafe to walk the
bus->devices list of a PCI bus and remove devices from it in direct order,
because that may lead to NULL pointer dereferences related to virtual
functions.

For this reason, change all of the bus->devices list walks in
acpiphp_glue.c during which devices may be removed to be carried out in
reverse order.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index cd929aed3613..6a4b4b734fbd 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -742,7 +742,7 @@ static void trim_stale_devices(struct pci_dev *dev)
 
                 /* The device is a bridge. so check the bus below it. */
                 pm_runtime_get_sync(&dev->dev);
-                list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
+                list_for_each_entry_safe_reverse(child, tmp, &bus->devices, bus_list)
                         trim_stale_devices(child);
 
                 pm_runtime_put(&dev->dev);
@@ -773,8 +773,8 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
                         ; /* do nothing */
                 } else if (get_slot_status(slot) == ACPI_STA_ALL) {
                         /* remove stale devices if any */
-                        list_for_each_entry_safe(dev, tmp, &bus->devices,
-                                                 bus_list)
+                        list_for_each_entry_safe_reverse(dev, tmp,
+                                                         &bus->devices, bus_list)
                                 if (PCI_SLOT(dev->devfn) == slot->device)
                                         trim_stale_devices(dev);
 
@@ -805,7 +805,7 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
         int i;
         unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM;
 
-        list_for_each_entry_safe(dev, tmp, &bus->devices, bus_list) {
+        list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) {
                 for (i=0; i<PCI_BRIDGE_RESOURCES; i++) {
                         struct resource *res = &dev->resource[i];
                         if ((res->flags & type_mask) && !res->start &&