From fc1b253141b360f9c669d391b4ff663b984ef0c9 Mon Sep 17 00:00:00 2001 From: Andreas Noever Date: Thu, 23 Jan 2014 21:59:28 +0100 Subject: [PATCH] PCI: Don't scan random busses in pci_scan_bridge() When assigning a new bus number in pci_scan_bridge we check whether max+1 is free by calling pci_find_bus. If it does already exist then we assume that we are rescanning and that this is the right bus to scan. This is fragile. If max+1 lies outside of bus->busn_res.end then we will rescan some random bus from somewhere else in the hierachy. This patch checks for this case and prints a warning. [bhelgaas: add parent/child bus number info to dev_warn()] Signed-off-by: Andreas Noever Signed-off-by: Bjorn Helgaas --- drivers/pci/probe.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 1436288924c3..509494381a7a 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -829,12 +829,16 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass) goto out; } + if (max >= bus->busn_res.end) { + dev_warn(&dev->dev, "can't allocate child bus %02x from %pR\n", + max, &bus->busn_res); + goto out; + } + /* Clear errors */ pci_write_config_word(dev, PCI_STATUS, 0xffff); - /* Prevent assigning a bus number that already exists. - * This can happen when a bridge is hot-plugged, so in - * this case we only re-scan this bus. */ + /* The bus will already exist if we are rescanning */ child = pci_find_bus(pci_domain_nr(bus), max+1); if (!child) { child = pci_add_new_bus(bus, dev, max+1);