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

[Navid Emamdoost]

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 returning -ENOMEM (I am not sure this is the best errno, you may 
consider it as a placeholder), and subsequently changing the caller’s 
return type, and propagating the error.

Signed-off-by: Navid Emamdoost <navid.emamdo...@gmail.com>
---
 drivers/tty/serial/8250/8250_lpss.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_lpss.c 
b/drivers/tty/serial/8250/8250_lpss.c
index 53ca9ba6ab4b..5954b2e09b76 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -161,7 +161,7 @@ static const struct dw_dma_platform_data 
qrk_serial_dma_pdata = {
        .multi_block = {0},
 };
 
-static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
+static int qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
 {
        struct uart_8250_dma *dma = &lpss->dma;
        struct dw_dma_chip *chip = &lpss->dma_chip;
@@ -172,12 +172,14 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, 
struct uart_port *port)
        chip->dev = &pdev->dev;
        chip->irq = pci_irq_vector(pdev, 0);
        chip->regs = pci_ioremap_bar(pdev, 1);
+       if (!chip->regs)
+               return -ENOMEM;
        chip->pdata = &qrk_serial_dma_pdata;
 
        /* Falling back to PIO mode if DMA probing fails */
        ret = dw_dma_probe(chip);
        if (ret)
-               return;
+               return 0;
 
        pci_try_set_mwi(pdev);
 
@@ -191,6 +193,7 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, 
struct uart_port *port)
        param->hs_polarity = true;
 
        lpss->dma_maxburst = 8;
+       return 0;
 }
 
 static void qrk_serial_exit_dma(struct lpss8250 *lpss)
@@ -219,7 +222,9 @@ static int qrk_serial_setup(struct lpss8250 *lpss, struct 
uart_port *port)
 
        port->irq = pci_irq_vector(pdev, 0);
 
-       qrk_serial_setup_dma(lpss, port);
+       ret = qrk_serial_setup_dma(lpss, port);
+       if (ret < 0)
+               return ret;
        return 0;
 }
 
-- 
2.17.1