2009-03-06 02:28:52

by Alex Chiang

Subject: [PATCH] PCIe: AER: during disable, check subordinate before walking

Commit 47a8b0cc (Enable PCIe AER only after checking firmware
support) wants to walk the PCI bus in the remove path to disable
AER, and calls pci_walk_bus for downstream bridges.

Unfortunately, in the remove path, we remove devices and bridges
in a depth-first manner, starting with the furthest downstream
bridge and working our way backwards.

The furthest downstream bridges will not have a dev->subordinate,
and we hit a NULL deref in pci_walk_bus.

Check for dev->subordinate first before attempting to walk the
PCI hierarchy below us.

Cc: Andrew Patterson <[email protected]>
Signed-off-by: Alex Chiang <[email protected]>
---
Willy, this is .29 material, please push to Linus, thanks.

---
diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
index aebb5f6..677d680 100644
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -133,6 +133,9 @@ static void set_downstream_devices_error_reporting(struct pci_dev *dev,
bool enable)
{
set_device_error_reporting(dev, &enable);
+
+ if (!dev->subordinate)
+ return;
pci_walk_bus(dev->subordinate, set_device_error_reporting, &enable);
}

2009-03-06 20:17:19

by Andrew Patterson

Subject: Re: [PATCH] PCIe: AER: during disable, check subordinate before walking

On Thu, 2009-03-05 at 19:28 -0700, Alex Chiang wrote:
> Commit 47a8b0cc (Enable PCIe AER only after checking firmware
> support) wants to walk the PCI bus in the remove path to disable
> AER, and calls pci_walk_bus for downstream bridges.
>
> Unfortunately, in the remove path, we remove devices and bridges
> in a depth-first manner, starting with the furthest downstream
> bridge and working our way backwards.
>
> The furthest downstream bridges will not have a dev->subordinate,
> and we hit a NULL deref in pci_walk_bus.
>
> Check for dev->subordinate first before attempting to walk the
> PCI hierarchy below us.
>

Looks good.

Acked-by: Andrew Patterson <[email protected]>

> Cc: Andrew Patterson <[email protected]>
> Signed-off-by: Alex Chiang <[email protected]>
> ---
> Willy, this is .29 material, please push to Linus, thanks.
>
> ---
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index aebb5f6..677d680 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -133,6 +133,9 @@ static void set_downstream_devices_error_reporting(struct pci_dev *dev,
> bool enable)
> {
> set_device_error_reporting(dev, &enable);
> +
> + if (!dev->subordinate)
> + return;
> pci_walk_bus(dev->subordinate, set_device_error_reporting, &enable);
> }
>

--
Andrew Patterson
Hewlett-Packard Company