[PATCH 7/8] PCI: Check for child busses which use more bus numbers than allocated.

From: Andreas Noever
Date: Thu Jan 23 2014 - 16:00:13 EST

pci_scan_child_bus can (potentially) return a bus number higher than the subordinate
value of the child bus. Possible reasons are that bus numbers are reserved for
SR-IOV or for CardBus (SR-IOV is done without checks and the CardBus
checks are sketchy at best).

We clamp the returned value to the actual subordinate value and print a
warning if too many bus numbers are reserved.

Signed-off-by: Andreas Noever <andreas.noever@xxxxxxxxx>
drivers/pci/probe.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 90d5c48..74bc644 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -805,10 +805,13 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)

cmax = pci_scan_child_bus(child);
- if (cmax > max)
- max = cmax;
- if (child->busn_res.end > max)
- max = child->busn_res.end;
+ if (cmax > subordinate)
+ dev_warn(&dev->dev,
+ "bridge has subordinate %02x but max busn %02x\n",
+ subordinate, cmax);
+ /* subordinate should equal child->busn_res.end */
+ if (subordinate > max)
+ max = subordinate;
} else {
* We need to assign a number to this bus which we always

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