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

Navid Emamdoost
2019-07-19T02:55:05Z

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.emamdoost@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