From 3fb937f441c64af1eec60bfd3732f64001fcc534 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Fri, 1 Oct 2021 15:58:10 +0200
Subject: [PATCH] PCI: ACPI: Check parent pointer in acpi_pci_find_companion()
Git-commit: 3fb937f441c64af1eec60bfd3732f64001fcc534
References: git-fixes
Patch-mainline: v5.15-rc5
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 commit 375553a93201 ("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: 375553a93201 ("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>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/pci/pci-acpi.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -1259,6 +1259,9 @@ static struct acpi_device *acpi_pci_find
if (adev)
return adev;
+ if (!dev->parent)
+ return NULL;
+
check_children = pci_is_bridge(pci_dev);
/* Please ref to ACPI spec for the syntax of _ADR */
addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn);