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From:   Kangjie Lu <kjlu@umn.edu>
To:     kjlu@umn.edu
Cc:     pakki001@umn.edu, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Michal Simek <michal.simek@xilinx.com>,
        linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v2] pci: pcie-xilinx: fix a missing-check bug for __get_free_pages
Date:   Mon, 25 Mar 2019 16:31:13 -0500
Message-Id: <20190325213113.24705-1-kjlu@umn.edu>
In-Reply-To: <d0aa29e9-54c6-bc8b-4827-0562b277265f@arm.com>
References: <d0aa29e9-54c6-bc8b-4827-0562b277265f@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In case __get_free_pages fail, the fix returns -ENOMEMto avoid
NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Reviewed-by: Steven Price <steven.price@arm.com>
---
v2: caller is redefined to accept the error code, as suggested by
Steven Price <steven.price@arm.com>
---
 drivers/pci/controller/pcie-xilinx.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
index 9bd1a35cd5d8..abc214e94f7c 100644
--- a/drivers/pci/controller/pcie-xilinx.c
+++ b/drivers/pci/controller/pcie-xilinx.c
@@ -336,14 +336,19 @@ static const struct irq_domain_ops msi_domain_ops = {
  * xilinx_pcie_enable_msi - Enable MSI support
  * @port: PCIe port information
  */
-static void xilinx_pcie_enable_msi(struct xilinx_pcie_port *port)
+static int xilinx_pcie_enable_msi(struct xilinx_pcie_port *port)
 {
 	phys_addr_t msg_addr;
 
 	port->msi_pages = __get_free_pages(GFP_KERNEL, 0);
+	if (unlikely(!port->msi_pages))
+		return -ENOMEM;
+
 	msg_addr = virt_to_phys((void *)port->msi_pages);
 	pcie_write(port, 0x0, XILINX_PCIE_REG_MSIBASE1);
 	pcie_write(port, msg_addr, XILINX_PCIE_REG_MSIBASE2);
+
+	return 0;
 }
 
 /* INTx Functions */
@@ -498,6 +503,7 @@ static int xilinx_pcie_init_irq_domain(struct xilinx_pcie_port *port)
 	struct device *dev = port->dev;
 	struct device_node *node = dev->of_node;
 	struct device_node *pcie_intc_node;
+	int ret;
 
 	/* Setup INTx */
 	pcie_intc_node = of_get_next_child(node, NULL);
@@ -526,7 +532,9 @@ static int xilinx_pcie_init_irq_domain(struct xilinx_pcie_port *port)
 			return -ENODEV;
 		}
 
-		xilinx_pcie_enable_msi(port);
+		ret = xilinx_pcie_enable_msi(port);
+		if (ret)
+			return ret;
 	}
 
 	return 0;
-- 
2.17.1