[PATCH v9 1/5] PCI: Add pcie_get_link_speed() helper for safe array access

[Manivannan Sadhasivam]

On Thu, Mar 26, 2026 at 01:16:24PM -0500, Bjorn Helgaas wrote:
> On Sat, Mar 14, 2026 at 12:55:18AM +0800, Hans Zhang wrote:
> > 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 at 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..409aca7d737a 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(unsigned 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..d6592898330c 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
> 
> Wrong name here (pcie_link_speed_value vs pcie_get_link_speed)
> (pointed out by Sashiko).
> 

Noticed this one while applying.

> > + * @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(unsigned int speed)
> 
> Sashiko also pointed out that the commit log says this returns "enum
> pci_bus_speed", while here we return unsigned char (which is also the
> type of pcie_link_speed[x]).
> 
> https://sashiko.dev/#/patchset/20260313165522.123518-1-18255117159%40163.com
> 

This one I didn't, but fixed now, thanks!

- Mani

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