[PATCH v2] tty: 8250: fix a missing check for pci_ioremap_bar

[Aditya Pakki]

pci_ioremap_bar could fail. The fix captures the failure and
pass an error code upstream. This can avoid potential NULL
pointer dereferences in the future.

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

---
v1: Missed return by default in CONFIG_SERIAL_8250_DMA, suggested by
Jiri Slaby
---
 drivers/tty/serial/8250/8250_lpss.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_lpss.c 
b/drivers/tty/serial/8250/8250_lpss.c
index 53ca9ba6ab4b..1dc67897dcf8 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 -EIO;
        chip->pdata = &qrk_serial_dma_pdata;
 
        /* Falling back to PIO mode if DMA probing fails */
        ret = dw_dma_probe(chip);
        if (ret)
-               return;
+               return ret;
 
        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)
@@ -202,7 +205,11 @@ static void qrk_serial_exit_dma(struct lpss8250 *lpss)
        dw_dma_remove(&lpss->dma_chip);
 }
 #else  /* CONFIG_SERIAL_8250_DMA */
-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)
+{
+       return 0;
+}
+
 static void qrk_serial_exit_dma(struct lpss8250 *lpss) {}
 #endif /* !CONFIG_SERIAL_8250_DMA */
 
@@ -219,8 +226,7 @@ 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);
-       return 0;
+       return qrk_serial_setup_dma(lpss, port);
 }
 
 static void qrk_serial_exit(struct lpss8250 *lpss)
-- 
2.17.1