[PATCH v8 1/5] PCI: Add pcie_get_link_speed() helper for safe array access

Hans Zhang
2026-03-12T16:38:17Z

The pcie_link_speed[] array is indexed by PCIe generation numbers
(1 = 2.5 GT/s, 2 = 5 GT/s, ...). Several drivers use it directly,
which can lead to out-of-bounds accesses if an invalid generation
number is used.

Introduce a helper function pcie_get_link_speed() that returns the
corresponding enum pci_bus_speed value for a given generation number,
or PCI_SPEED_UNKNOWN if the generation is out of range. This will
allow us to safely handle invalid values after the range check is
removed from of_pci_get_max_link_speed().

Signed-off-by: Hans Zhang <18255117159@163.com>
---
drivers/pci/pci.h | 2 ++
drivers/pci/probe.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 13d998fbacce..6bf3e59f42e5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -108,6 +108,8 @@ struct pcie_tlp_log;
PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE)

extern const unsigned char pcie_link_speed[];
+unsigned char pcie_get_link_speed(int speed);
+
extern bool pci_early_dump;

extern struct mutex pci_rescan_remove_lock;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index bccc7a4bdd79..a95afbcee421 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -783,6 +783,22 @@ const unsigned char pcie_link_speed[] = {
};
EXPORT_SYMBOL_GPL(pcie_link_speed);

+/**
+ * pcie_link_speed_value - Get speed value from PCIe generation number
+ * @speed: PCIe speed (1-based: 1 = 2.5GT, 2 = 5GT, ...)
+ *
+ * Returns the speed value (e.g., PCIE_SPEED_2_5GT) if @speed is valid,
+ * otherwise returns PCI_SPEED_UNKNOWN.
+ */
+unsigned char pcie_get_link_speed(int speed)
+{
+ if (speed <= 0 || speed >= ARRAY_SIZE(pcie_link_speed))
+ return PCI_SPEED_UNKNOWN;
+
+ return pcie_link_speed[speed];
+}
+EXPORT_SYMBOL_GPL(pcie_get_link_speed);
+
const char *pci_speed_string(enum pci_bus_speed speed)
{
/* Indexed by the pci_bus_speed enum */
--
2.34.1