diff mbox series

PCI: ACPI: Check parent pointer in acpi_pci_find_companion()

Message ID 5523582.DvuYhMxLoT@kreacher (mailing list archive)
State Not Applicable
Delegated to: Bjorn Helgaas
Headers show
Series PCI: ACPI: Check parent pointer in acpi_pci_find_companion() | expand

Commit Message

Rafael J. Wysocki Oct. 1, 2021, 1:58 p.m. UTC
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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>
---
 drivers/pci/pci-acpi.c |    3 +++
 1 file changed, 3 insertions(+)

Comments

Rafael J. Wysocki Oct. 5, 2021, 1:46 p.m. UTC | #1
On Fri, Oct 1, 2021 at 3:58 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> 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>

Due to the lack of negative feedback I'm queuing this up for 5.15-rc5.
If there are concerns, please let me know.

> ---
>  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 ?
>
>
>
Bjorn Helgaas Oct. 6, 2021, 6:58 p.m. UTC | #2
On Fri, Oct 01, 2021 at 03:58:10PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> 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>

> ---
>  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 ?
> 
> 
>
diff mbox series

Patch

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 ?