Re: [PATCH] PCI: Prevent NULL dereference during pciehp probe

[Bjorn Helgaas]

On Tue, Sep 23, 2014 at 3:55 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> On Mon, Sep 15, 2014 at 10:20:41PM +0000, Rajat Jain wrote:
>> Hello Bjorn,
>>
>> I think this patch needs to be applied to all -stable branches (all the way back to 3.2).
>>
>> I encounter this same issue on my platform that is running 3.14.y.
>>
> Bjorn,
>
> can you send this to -stable, or is it ok if I do it ?

I forgot to mention it, but I did mark it for stable, so it should
happen automatically:

https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?h=pci/hotplug&id=bceee4a97eb58bd0e80e39eff11b506ddd9e7ad3

>> > -----Original Message-----
>> > From: linux-pci-owner@xxxxxxxxxxxxxxx [mailto:linux-pci-
>> > owner@xxxxxxxxxxxxxxx] On Behalf Of Andreas Noever
>> > Sent: Monday, June 09, 2014 2:04 PM
>> > To: linux-kernel@xxxxxxxxxxxxxxx; Bjorn Helgaas; linux-pci@xxxxxxxxxxxxxxx
>> > Cc: Andreas Noever
>> > Subject: [PATCH] PCI: Prevent NULL dereference during pciehp probe
>> >
>> > pciehp assumes that dev->subordinate exists. But we do not assign a bus if
>> > we run out of bus numbers during enumeration. This leads to a NULL
>> > dereference in init_slot (and other places).
>> >
>> > Change pciehp_probe to return -ENODEV when no subordinate bus is
>> > present.
>> >
>> > Signed-off-by: Andreas Noever <andreas.noever@xxxxxxxxx>
>> > ---
>> >  drivers/pci/hotplug/pciehp_core.c | 7 +++++++
>> >  1 file changed, 7 insertions(+)
>> >
>> > diff --git a/drivers/pci/hotplug/pciehp_core.c
>> > b/drivers/pci/hotplug/pciehp_core.c
>> > index 0e0a2ff..e5abcaf 100644
>> > --- a/drivers/pci/hotplug/pciehp_core.c
>> > +++ b/drivers/pci/hotplug/pciehp_core.c
>> > @@ -255,6 +255,13 @@ static int pciehp_probe(struct pcie_device *dev)
>> >     else if (pciehp_acpi_slot_detection_check(dev->port))
>> >             goto err_out_none;
>> >
>> > +   if (!dev->port->subordinate) {
>> > +           /* Can happen if we run out of bus numbers during probe */
>> > +           dev_err(&dev->device,
>> > +                   "Hotplug bridge without secondary bus, ignoring\n");
>> > +           goto err_out_none;
>> > +   }
>> > +
>> >     ctrl = pcie_init(dev);
>> >     if (!ctrl) {
>> >             dev_err(&dev->device, "Controller initialization failed\n");
>> > --
>> > 2.0.0
>> >
>> > --
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