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If acpi_pci_find_companion() is called for a device whose parent pointer is NULL, it will crash when attempting to get the ACPI companion of the parent due to a NULL pointer dereference in the ACPI_COMPANION() macro. This was not a problem before commit375553a932("PCI: Setup ACPI fwnode early and at the same time with OF") that made pci_setup_device() call pci_set_acpi_fwnode() and so it allowed devices with NULL parent pointers to be passed to acpi_pci_find_companion() which is the case in pci_iov_add_virtfn(), for instance. Fix this issue by making acpi_pci_find_companion() check the device's parent pointer upfront and bail out if it is NULL. While pci_iov_add_virtfn() can be changed to set the device's parent pointer before calling pci_setup_device() for it, checking pointers against NULL before dereferencing them is prudent anyway and looking for ACPI companions of virtual functions isn't really useful. Fixes:375553a932("PCI: Setup ACPI fwnode early and at the same time with OF") Link: https://lore.kernel.org/linux-acpi/8e4bbd5c59de31db71f718556654c0aa077df03d.camel@linux.ibm.com/ Reported-by: Niklas Schnelle <schnelle@linux.ibm.com> Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.