From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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@xxxxxxxxxxxxx/
Reported-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Tested-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
drivers/pci/pci-acpi.c | 3 +++
1 file changed, 3 insertions(+)
Index: linux-pm/drivers/pci/pci-acpi.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-acpi.c
+++ linux-pm/drivers/pci/pci-acpi.c
@@ -1243,6 +1243,9 @@ static struct acpi_device *acpi_pci_find
bool check_children;
u64 addr;
+ if (!dev->parent)
+ return NULL;
+
down_read(&pci_acpi_companion_lookup_sem);
adev = pci_acpi_find_companion_hook ?
