From 3fb937f441c64af1eec60bfd3732f64001fcc534 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 1 Oct 2021 15:58:10 +0200 Subject: [PATCH] PCI: ACPI: Check parent pointer in acpi_pci_find_companion() 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 Tested-by: Niklas Schnelle Signed-off-by: Rafael J. Wysocki Acked-by: Bjorn Helgaas --- drivers/pci/pci-acpi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 0f40943a9a18a..260a06fb78a61 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1249,6 +1249,9 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev) bool check_children; u64 addr; + if (!dev->parent) + return NULL; + down_read(&pci_acpi_companion_lookup_sem); adev = pci_acpi_find_companion_hook ? -- 2.30.2