This is a note to let you know that I've just added the patch titled

PCI: Do not allocate more buses than available in parent

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: pci-do-not-allocate-more-buses-than-available-in-parent.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Mon Dec 18 13:28:59 CET 2017

From: Mika Westerberg mika.westerberg@linux.intel.com Date: Fri, 13 Oct 2017 21:35:43 +0300 Subject: PCI: Do not allocate more buses than available in parent

From: Mika Westerberg mika.westerberg@linux.intel.com

[ Upstream commit a20c7f36bd3d20d245616ae223bb9d05dfb6f050 ]

One can ask more buses to be reserved for hotplug bridges by passing pci=hpbussize=N in the kernel command line. If the parent bus does not have enough bus space available we incorrectly create child bus with the requested number of subordinate buses.

In the example below hpbussize is set to one more than we have available buses in the root port:

pci 0000:07:00.0: [8086:1578] type 01 class 0x060400 pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 0 pci 0000:07:00.0: bridge configuration invalid ([bus 00-00]), reconfiguring pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 1 pci_bus 0000:08: busn_res: can not insert [bus 08-ff] under [bus 07-3f] (conflicts with (null) [bus 07-3f]) pci_bus 0000:08: scanning bus ... pci_bus 0000:0a: bus scan returning with max=40 pci_bus 0000:0a: busn_res: [bus 0a-ff] end is updated to 40 pci_bus 0000:0a: [bus 0a-40] partially hidden behind bridge 0000:07 [bus 07-3f] pci_bus 0000:08: bus scan returning with max=40 pci_bus 0000:08: busn_res: [bus 08-ff] end is updated to 40

Instead of allowing this, limit the subordinate number to be less than or equal the maximum subordinate number allocated for the parent bus (if it has any).

Signed-off-by: Mika Westerberg mika.westerberg@linux.intel.com [bhelgaas: remove irrelevant dmesg messages] Signed-off-by: Bjorn Helgaas bhelgaas@google.com

Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/probe.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1076,7 +1076,8 @@ int pci_scan_bridge(struct pci_bus *bus, child = pci_add_new_bus(bus, dev, max+1); if (!child) goto out; - pci_bus_insert_busn_res(child, max+1, 0xff); + pci_bus_insert_busn_res(child, max+1, + bus->busn_res.end); } max++; buses = (buses & 0xff000000) @@ -2433,6 +2434,10 @@ unsigned int pci_scan_child_bus(struct p if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) { if (max - bus->busn_res.start < pci_hotplug_bus_size - 1) max = bus->busn_res.start + pci_hotplug_bus_size - 1; + + /* Do not allocate more buses than we have room left */ + if (max > bus->busn_res.end) + max = bus->busn_res.end; }

/*

Patches currently in stable-queue which might be from mika.westerberg@linux.intel.com are

queue-4.14/thunderbolt-tb-fix-use-after-free-in-tb_activate_pcie_devices.patch queue-4.14/pci-do-not-allocate-more-buses-than-available-in-parent.patch