2020-07-06 10:32:36

by Saheed O. Bolarinwa

Subject: [PATCH 7/11 RFC] PCI: Validate with 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 11/11, 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_dword
is checked to confirm success.

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

Suggested-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Bolarinwa Olayemi Saheed <[email protected]>
---
drivers/pci/probe.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2f66988cea25..3c87a8a1d4b5 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1121,10 +1121,11 @@ EXPORT_SYMBOL(pci_add_new_bus);
static void pci_enable_crs(struct pci_dev *pdev)
{
u16 root_cap = 0;
+ int ret;

/* Enable CRS Software Visibility if supported */
- pcie_capability_read_word(pdev, PCI_EXP_RTCAP, &root_cap);
- if (root_cap & PCI_EXP_RTCAP_CRSVIS)
+ ret = pcie_capability_read_word(pdev, PCI_EXP_RTCAP, &root_cap);
+ if (!ret && (root_cap & PCI_EXP_RTCAP_CRSVIS))
pcie_capability_set_word(pdev, PCI_EXP_RTCTL,
PCI_EXP_RTCTL_CRSSVE);
}
@@ -1519,9 +1520,10 @@ void set_pcie_port_type(struct pci_dev *pdev)
void set_pcie_hotplug_bridge(struct pci_dev *pdev)
{
u32 reg32;
+ int ret;

- pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &reg32);
- if (reg32 & PCI_EXP_SLTCAP_HPC)
+ ret = pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &reg32);
+ if (!ret && (reg32 & PCI_EXP_SLTCAP_HPC))
pdev->is_hotplug_bridge = 1;
}

@@ -2057,10 +2059,11 @@ int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
bool pcie_relaxed_ordering_enabled(struct pci_dev *dev)
{
u16 v;
+ int ret;

- pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);
+ ret = pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &v);

- return !!(v & PCI_EXP_DEVCTL_RELAX_EN);
+ return (!ret && !!(v & PCI_EXP_DEVCTL_RELAX_EN));
}
EXPORT_SYMBOL(pcie_relaxed_ordering_enabled);

@@ -2096,16 +2099,17 @@ static void pci_configure_ltr(struct pci_dev *dev)
struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
struct pci_dev *bridge;
u32 cap, ctl;
+ int ret;

if (!pci_is_pcie(dev))
return;

- pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
- if (!(cap & PCI_EXP_DEVCAP2_LTR))
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+ if (ret || !(cap & PCI_EXP_DEVCAP2_LTR))
return;

- pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl);
- if (ctl & PCI_EXP_DEVCTL2_LTR_EN) {
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCTL2, &ctl);
+ if (!ret && (ctl & PCI_EXP_DEVCTL2_LTR_EN)) {
if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
dev->ltr_path = 1;
return;
@@ -2142,12 +2146,13 @@ static void pci_configure_eetlp_prefix(struct pci_dev *dev)
struct pci_dev *bridge;
int pcie_type;
u32 cap;
+ int ret;

if (!pci_is_pcie(dev))
return;

- pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
- if (!(cap & PCI_EXP_DEVCAP2_EE_PREFIX))
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+ if (ret || !(cap & PCI_EXP_DEVCAP2_EE_PREFIX))
return;

pcie_type = pci_pcie_type(dev);
--
2.18.2