[PATCH v4 1/3] PCI: dwc: allow to limit registers set length

[Stefan Agner]

Add length to the struct dw_pcie and check that the accessors
dw_pcie_(rd|wr)_conf() do not read/write beyond that point.

Suggested-by: Trent Piepho <tpie...@impinj.com>
Signed-off-by: Stefan Agner <ste...@agner.ch>
---
Changes in v4:
- Move length check to dw_pcie_rd_conf

 .../pci/controller/dwc/pcie-designware-host.c    | 16 ++++++++++++++--
 drivers/pci/controller/dwc/pcie-designware.h     |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c 
b/drivers/pci/controller/dwc/pcie-designware-host.c
index 692dd1b264fb..9fc0f7bd99f0 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -606,14 +606,20 @@ static int dw_pcie_rd_conf(struct pci_bus *bus, u32 
devfn, int where,
                           int size, u32 *val)
 {
        struct pcie_port *pp = bus->sysdata;
+       struct dw_pcie *pci;
 
        if (!dw_pcie_valid_device(pp, bus, PCI_SLOT(devfn))) {
                *val = 0xffffffff;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }
 
-       if (bus->number == pp->root_bus_nr)
+       if (bus->number == pp->root_bus_nr) {
+               pci = to_dw_pcie_from_pp(pp);
+               if (pci->dbi_length && where + size > pci->dbi_length)
+                       return PCIBIOS_BAD_REGISTER_NUMBER;
+
                return dw_pcie_rd_own_conf(pp, where, size, val);
+       }
 
        return dw_pcie_rd_other_conf(pp, bus, devfn, where, size, val);
 }
@@ -622,12 +628,18 @@ static int dw_pcie_wr_conf(struct pci_bus *bus, u32 devfn,
                           int where, int size, u32 val)
 {
        struct pcie_port *pp = bus->sysdata;
+       struct dw_pcie *pci;
 
        if (!dw_pcie_valid_device(pp, bus, PCI_SLOT(devfn)))
                return PCIBIOS_DEVICE_NOT_FOUND;
 
-       if (bus->number == pp->root_bus_nr)
+       if (bus->number == pp->root_bus_nr) {
+               pci = to_dw_pcie_from_pp(pp);
+               if (pci->dbi_length && where + size > pci->dbi_length)
+                       return PCIBIOS_BAD_REGISTER_NUMBER;
+
                return dw_pcie_wr_own_conf(pp, where, size, val);
+       }
 
        return dw_pcie_wr_other_conf(pp, bus, devfn, where, size, val);
 }
diff --git a/drivers/pci/controller/dwc/pcie-designware.h 
b/drivers/pci/controller/dwc/pcie-designware.h
index 9943d8c68335..9cd7bdc94200 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -229,6 +229,7 @@ struct dw_pcie {
        void __iomem            *dbi_base2;
        /* Used when iatu_unroll_enabled is true */
        void __iomem            *atu_base;
+       int                     dbi_length;
        u32                     num_viewport;
        u8                      iatu_unroll_enabled;
        struct pcie_port        pp;
-- 
2.19.1