[PATCH v3] 8250_lpss: check null return when calling pci_ioremap_bar

Navid Emamdoost
2019-07-26T19:54:12Z

pci_ioremap_bar may return null. This is eventually de-referenced at
drivers/dma/dw/core.c:1154 and drivers/dma/dw/core.c:1168. A null check
is needed to prevent null de-reference. I am adding the check and in case
of failure. Thanks to Andy Shevchenko for the hint on the necessity of
pci_iounmap when exiting.
Update: also covered the dw_dma_probe() failure.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
drivers/tty/serial/8250/8250_lpss.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
index 53ca9ba6ab4b..19b356119ef6 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -169,15 +169,20 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
struct pci_dev *pdev = to_pci_dev(port->dev);
int ret;

+ chip->pdata = &qrk_serial_dma_pdata;
chip->dev = &pdev->dev;
chip->irq = pci_irq_vector(pdev, 0);
chip->regs = pci_ioremap_bar(pdev, 1);
- chip->pdata = &qrk_serial_dma_pdata;
+ if (!chip->regs)
+ return;

/* Falling back to PIO mode if DMA probing fails */
ret = dw_dma_probe(chip);
- if (ret)
+ if (ret) {
+ dw_dma_remove(chip);
+ pci_iounmap(to_pci_dev(chip->dev), chip->regs);
return;
+ }

pci_try_set_mwi(pdev);

@@ -195,11 +200,15 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)

static void qrk_serial_exit_dma(struct lpss8250 *lpss)
{
+ struct dw_dma_chip *chip = &lpss->dma_chip;
struct dw_dma_slave *param = &lpss->dma_param;

if (!param->dma_dev)
return;
- dw_dma_remove(&lpss->dma_chip);
+
+ dw_dma_remove(chip);
+
+ pci_iounmap(to_pci_dev(chip->dev), chip->regs);
}
#else /* CONFIG_SERIAL_8250_DMA */
static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}
--
2.17.1