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From:   Stefan Agner <stefan@agner.ch>
To:     lorenzo.pieralisi@arm.com, jingoohan1@gmail.com,
        gustavo.pimentel@synopsys.com, l.stach@pengutronix.de,
        tpiepho@impinj.com
Cc:     leonard.crestez@nxp.com, bhelgaas@google.com,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        stefan@agner.ch
Subject: [PATCH 1/2] PCI: dwc: allow to limit registers set length
Date:   Wed,  6 Feb 2019 10:57:31 +0100
Message-Id: <14fafdf52d19feb9c926c312f4e3ba7ff8a4bad9.1549446867.git.stefan@agner.ch>
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Sender: linux-kernel-owner@vger.kernel.org
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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 <tpiepho@impinj.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
---
Changes in v4:
- Move length check to dw_pcie_rd_conf
Changes in v5:
- Rebased ontop of pci/dwc

 .../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 45ff5e4f8af6..bad54204fb52 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -612,14 +612,20 @@ 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);
 }
@@ -628,12 +634,18 @@ 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 279000255ad1..d1d95119a422 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -226,6 +226,7 @@ struct dw_pcie_ops {
 struct dw_pcie {
 	struct device		*dev;
 	void __iomem		*dbi_base;
+	int			dbi_length;
 	void __iomem		*dbi_base2;
 	/* Used when iatu_unroll_enabled is true */
 	void __iomem		*atu_base;
-- 
2.20.1