linux-kernel - [05/38] Fix pointer dereference before call to pcie_bus_configure

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Date:	Tue, 11 Oct 2011 10:55:15 -0600
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Shyam Iyer <shyam_iyer@...l.com>, Jon Mason <mason@...i.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: [05/38] Fix pointer dereference before call to pcie_bus_configure_settings

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Shyam Iyer <shyam.iyer.t@...il.com>

commit 5307f6d5fb12fd01f9f321bc4a8fd77e74858647 upstream.

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@...hat.com>
Signed-off-by: Shyam Iyer <shyam_iyer@...l.com>
Signed-off-by: Jon Mason <mason@...i.com>
Acked-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/pci/acpi.c              |    9 +++++++--
 drivers/pci/hotplug/pcihp_slot.c |    4 +++-
 drivers/pci/probe.c              |    3 ---
 3 files changed, 10 insertions(+), 6 deletions(-)

--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -366,8 +366,13 @@ struct pci_bus * __devinit pci_acpi_scan
 	 */
 	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)
--- 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->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);
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1461,9 +1461,6 @@ void pcie_bus_configure_settings(struct
 {
 	u8 smpss = mpss;
 
-	if (!bus->self)
-		return;
-
 	if (!pci_is_pcie(bus->self))
 		return;
 


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