Re: [PATCH] ACPI / PCI: Fix NULL pointer dereference in acpi_get_pci_dev() (rev. 2)

[Alex Chiang <achiang@hp.com>]

* Rafael J. Wysocki <rjw@sisk.pl>:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> acpi_get_pci_dev() may be called for a non-PCI device, in which case
> it should return NULL.  However, it assumes that every handle it
> finds in the ACPI CA name space, between given device handle and the
> PCI root bridge handle, corresponds to a PCI-to-PCI bridge with an
> existing secondary bus.  For this reason, when it finds a struct
> pci_dev object corresponding to one of them, it doesn't check if
> its 'subordinate' field is a valid pointer.  This obviously leads to
> a NULL pointer dereference if acpi_get_pci_dev() is called for a
> non-PCI device with a PCI parent which is not a bridge.
> 
> To fix this issue make acpi_get_pci_dev() check if pdev->subordinate
> is not NULL for every device it finds on the path between the root
> bridge and the device it's supposed to get to and return NULL if the
> "target" device cannot be found.
> 
> Fixes http://bugzilla.kernel.org/show_bug.cgi?id=14129, which is a
> regression from 2.6.30.
 
Acked-by: Alex Chiang <achiang@hp.com>

> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
> 
> Jesse, Len,
> 
> This is a replacement for the original $subject patch (now in the Len's tree
> as commit 5988eaded02e3cca2702f46efc255143468255bd).
> 
> The code was correct, but the comment and the changelog were not.  Please
> use the one below instead.
> 
> Thanks,
> Rafael
>