From 29ed1f29b68a8395d5679b3c4e38352b617b3236 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 19 Jul 2013 12:14:16 -0700 Subject: [PATCH] PCI: pciehp: Fix null pointer deref when hot-removing SR-IOV device Hot-removing a device with SR-IOV enabled causes a null pointer dereference in v3.9 and v3.10. This is a regression caused by ba518e3c17 ("PCI: pciehp: Iterate over all devices in slot, not functions 0-7"). When we iterate over the bus->devices list, we first remove the PF, which also removes all the VFs from the list. Then the list iterator blows up because more than just the current entry was removed from the list. ac205b7bb7 ("PCI: make sriov work with hotplug remove") works around a similar problem in pci_stop_bus_devices() by iterating over the list in reverse, so the VFs are stopped and removed from the list first, before the PF. This patch changes pciehp_unconfigure_device() to iterate over the list in reverse, too. [bhelgaas: bugzilla, changelog] Reference: https://bugzilla.kernel.org/show_bug.cgi?id=60604 Signed-off-by: Yinghai Lu Signed-off-by: Bjorn Helgaas Acked-by: Yijing Wang CC: stable@vger.kernel.org # v3.9+ --- drivers/pci/hotplug/pciehp_pci.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/pci/hotplug/pciehp_pci.c b/drivers/pci/hotplug/pciehp_pci.c index aac7a40e4a4a..0e0d0f7f63fd 100644 --- a/drivers/pci/hotplug/pciehp_pci.c +++ b/drivers/pci/hotplug/pciehp_pci.c @@ -92,7 +92,14 @@ int pciehp_unconfigure_device(struct slot *p_slot) if (ret) presence = 0; - list_for_each_entry_safe(dev, temp, &parent->devices, bus_list) { + /* + * Stopping an SR-IOV PF device removes all the associated VFs, + * which will update the bus->devices list and confuse the + * iterator. Therefore, iterate in reverse so we remove the VFs + * first, then the PF. We do the same in pci_stop_bus_device(). + */ + list_for_each_entry_safe_reverse(dev, temp, &parent->devices, + bus_list) { pci_dev_get(dev); if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE && presence) { pci_read_config_byte(dev, PCI_BRIDGE_CONTROL, &bctl);