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SubjectRe: [PATCH v2] pci: pcie-xilinx: fix a missing-check bug for __get_free_pages
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On 23/03/2019 21:04, Aditya Pakki wrote:
> In case __get_free_pages fail, the fix returns error upstream
> to avoid NULL pointer dereference.

Where does msi_pages ever get dereferenced?

The logic here might actually still have a chance of working out OK with
NULL depending on how the memory maps line up, but even if it doesn't,
the problem is certainly not one of dereferencing.

Robin.

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

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