Fix pointer dereference before call to pcie_bus_configure_settings

Commit b03e7495a862 ("PCI: Set PCI-E Max Payload Size on fabric")
introduced a potential NULL pointer dereference in calls to
pcie_bus_configure_settings due to attempts to access pci_bus self
variables when the self pointer is NULL.

To correct this, verify that the self pointer in pci_bus is non-NULL
before dereferencing it.

Reported-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Shyam Iyer <shyam_iyer@dell.com>
Signed-off-by: Jon Mason <mason@myri.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index c953302..039d913 100644 (file)
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -365,8 +365,13 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root)
         */
        if (bus) {
                struct pci_bus *child;
-               list_for_each_entry(child, &bus->children, node)
-                       pcie_bus_configure_settings(child, child->self->pcie_mpss);
+               list_for_each_entry(child, &bus->children, node) {
+                       struct pci_dev *self = child->self;
+                       if (!self)
+                               continue;
+
+                       pcie_bus_configure_settings(child, self->pcie_mpss);
+               }
        }
 
        if (!bus)

diff --git a/drivers/pci/hotplug/pcihp_slot.c b/drivers/pci/hotplug/pcihp_slot.c
index 753b21a..3ffd9c1 100644 (file)
--- a/drivers/pci/hotplug/pcihp_slot.c
+++ b/drivers/pci/hotplug/pcihp_slot.c
@@ -169,7 +169,9 @@ void pci_configure_slot(struct pci_dev *dev)
                        (dev->class >> 8) == PCI_CLASS_BRIDGE_PCI)))
                return;
 
-       pcie_bus_configure_settings(dev->bus, dev->bus->self->pcie_mpss);
+       if (dev->bus && dev->bus->self)
+               pcie_bus_configure_settings(dev->bus,
+                                           dev->bus->self->pcie_mpss);
 
        memset(&hpp, 0, sizeof(hpp));
        ret = pci_get_hp_params(dev, &hpp);

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 8473727..0820fc1 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1456,9 +1456,6 @@ void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss)
 {
        u8 smpss = mpss;
 
-       if (!bus->self)
-               return;
-
        if (!pci_is_pcie(bus->self))
                return;