[PATCH 3/4] [Zesty] powerpc/powernv: Add sanity checks to pnv_pci_get_{gpu|npu}_dev

[Breno Leitao]

From: Alistair Popple <alistair at popple.id.au>

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1690412

The pnv_pci_get_{gpu|npu}_dev functions are used to find associations
between nvlink PCIe devices and standard PCIe devices. However they
lacked basic sanity checking which results in NULL pointer
dereferencing if they are incorrect called can be harder to spot than
an explicit WARN_ON.

Signed-off-by: Alistair Popple <alistair at popple.id.au>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
(cherry picked from commit 4c3b89effc281704d5395282c800c45e453235f6)
Signed-off-by: Breno Leitao <breno.leitao at gmail.com>
---
 arch/powerpc/platforms/powernv/npu-dma.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
index 73b155fd4481..1ab35f4957a6 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c
@@ -37,6 +37,12 @@ struct pci_dev *pnv_pci_get_gpu_dev(struct pci_dev *npdev)
 	struct device_node *dn;
 	struct pci_dev *gpdev;
 
+	if (WARN_ON(!npdev))
+		return NULL;
+
+	if (WARN_ON(!npdev->dev.of_node))
+		return NULL;
+
 	/* Get assoicated PCI device */
 	dn = of_parse_phandle(npdev->dev.of_node, "ibm,gpu", 0);
 	if (!dn)
@@ -55,6 +61,12 @@ struct pci_dev *pnv_pci_get_npu_dev(struct pci_dev *gpdev, int index)
 	struct device_node *dn;
 	struct pci_dev *npdev;
 
+	if (WARN_ON(!gpdev))
+		return NULL;
+
+	if (WARN_ON(!gpdev->dev.of_node))
+		return NULL;
+
 	/* Get assoicated PCI device */
 	dn = of_parse_phandle(gpdev->dev.of_node, "ibm,npu", index);
 	if (!dn)
-- 
2.11.0