linux-kernel - [PATCH v2] pci: pcie-xilinx: fix a missing-check bug for __get_free

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Date:   Sat, 23 Mar 2019 16:04:23 -0500
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] pci: pcie-xilinx: fix a missing-check bug for __get_free_pages

In case __get_free_pages fail, the fix returns error upstream
to avoid NULL pointer dereference.

Signed-off-by: Aditya Pakki <pakki001@....edu>

---
v1: Return error upstream as suggested by Steven
---
 drivers/pci/controller/pcie-xilinx.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
index 9bd1a35cd5d8..91d8945bfb0c 100644
--- a/drivers/pci/controller/pcie-xilinx.c
+++ b/drivers/pci/controller/pcie-xilinx.c
@@ -335,15 +335,19 @@ static const struct irq_domain_ops msi_domain_ops = {
 /**
  * xilinx_pcie_enable_msi - Enable MSI support
  * @port: PCIe port information
+ * Return: 0 on success, negative error on failure
  */
-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 (!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 +502,7 @@ 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 +531,9 @@ 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