2020-07-13 16:56:04

by Saheed O. Bolarinwa

Subject: [PATCH 8/14 v3] PCI/ACPI: Check the return value of pcie_capability_read_*()

From: Bolarinwa Olayemi Saheed <[email protected]>

On failure pcie_capability_read_dword() sets it's last parameter,
val to 0.
However, with Patch 14/14, it is possible that val is set to ~0 on
failure. This would introduce a bug because (x & x) == (~0 & x).

This bug can be avoided if the return value of pcie_capability_read_word
is checked to confirm success.

Check the return value of pcie_capability_read_word() to ensure success.

Suggested-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Bolarinwa Olayemi Saheed <[email protected]>
---
drivers/pci/pci-acpi.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 7224b1e5f2a8..39eb816bc3b8 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -248,12 +248,13 @@ static bool pcie_root_rcb_set(struct pci_dev *dev)
{
struct pci_dev *rp = pcie_find_root_port(dev);
u16 lnkctl;
+ int ret;

if (!rp)
return false;

- pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
- if (lnkctl & PCI_EXP_LNKCTL_RCB)
+ ret = pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
+ if (!ret && (lnkctl & PCI_EXP_LNKCTL_RCB))
return true;

return false;
@@ -792,12 +793,13 @@ bool pciehp_is_native(struct pci_dev *bridge)
{
const struct pci_host_bridge *host;
u32 slot_cap;
+ int ret;

if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
return false;

- pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
- if (!(slot_cap & PCI_EXP_SLTCAP_HPC))
+ ret = pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
+ if (ret || !(slot_cap & PCI_EXP_SLTCAP_HPC))
return false;

if (pcie_ports_native)
--
2.18.2

2020-07-14 13:29:08

by Rafael J. Wysocki

Subject: Re: [PATCH 8/14 v3] PCI/ACPI: Check the return value of pcie_capability_read_*()

On Mon, Jul 13, 2020 at 6:55 PM Saheed O. Bolarinwa
<[email protected]> wrote:
>
> From: Bolarinwa Olayemi Saheed <[email protected]>
>
> On failure pcie_capability_read_dword() sets it's last parameter,
> val to 0.
> However, with Patch 14/14, it is possible that val is set to ~0 on
> failure. This would introduce a bug because (x & x) == (~0 & x).
>
> This bug can be avoided if the return value of pcie_capability_read_word
> is checked to confirm success.
>
> Check the return value of pcie_capability_read_word() to ensure success.
>
> Suggested-by: Bjorn Helgaas <[email protected]>
> Signed-off-by: Bolarinwa Olayemi Saheed <[email protected]>

Acked-by: Rafael J. Wysocki <[email protected]>

> ---
> drivers/pci/pci-acpi.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 7224b1e5f2a8..39eb816bc3b8 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -248,12 +248,13 @@ static bool pcie_root_rcb_set(struct pci_dev *dev)
> {
> struct pci_dev *rp = pcie_find_root_port(dev);
> u16 lnkctl;
> + int ret;
>
> if (!rp)
> return false;
>
> - pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
> - if (lnkctl & PCI_EXP_LNKCTL_RCB)
> + ret = pcie_capability_read_word(rp, PCI_EXP_LNKCTL, &lnkctl);
> + if (!ret && (lnkctl & PCI_EXP_LNKCTL_RCB))
> return true;
>
> return false;
> @@ -792,12 +793,13 @@ bool pciehp_is_native(struct pci_dev *bridge)
> {
> const struct pci_host_bridge *host;
> u32 slot_cap;
> + int ret;
>
> if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
> return false;
>
> - pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
> - if (!(slot_cap & PCI_EXP_SLTCAP_HPC))
> + ret = pcie_capability_read_dword(bridge, PCI_EXP_SLTCAP, &slot_cap);
> + if (ret || !(slot_cap & PCI_EXP_SLTCAP_HPC))
> return false;
>
> if (pcie_ports_native)
> --
> 2.18.2
>