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[PATCH v1] tty: serial: 8250: 8250_gsc:- Handle return NULL error from ioremap_nocache

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  [PATCH v1] tty: serial: 8250: 8250_gsc:- Handle return NULL error from ioremap_nocache Arvind Yadav <arvind.yadav.cs@gmail.com> - 2017-01-19 09:10 +0100
    Re: [PATCH v1] tty: serial: 8250: 8250_gsc:- Handle return NULL error  from ioremap_nocache Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-01-19 20:00 +0100

#1562450 — [PATCH v1] tty: serial: 8250: 8250_gsc:- Handle return NULL error from ioremap_nocache

Here, If ioremap_nocache will fail. It will return NULL.
Kernel can run into a NULL-pointer dereference.
This error check will avoid NULL pointer dereference.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
---
 drivers/tty/serial/8250/8250_gsc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_gsc.c b/drivers/tty/serial/8250/8250_gsc.c
index b1e6ae9..63306de 100644
--- a/drivers/tty/serial/8250/8250_gsc.c
+++ b/drivers/tty/serial/8250/8250_gsc.c
@@ -60,6 +60,10 @@ static int __init serial_init_chip(struct parisc_device *dev)
 					7272727 : 1843200;
 	uart.port.mapbase	= address;
 	uart.port.membase	= ioremap_nocache(address, 16);
+	if (!uart.port.membase) {
+		dev_warn(&dev->dev, "Failed to map memory\n");
+		return -ENOMEM;
+	}
 	uart.port.irq	= dev->irq;
 	uart.port.flags	= UPF_BOOT_AUTOCONF;
 	uart.port.dev	= &dev->dev;
-- 
1.9.1

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#1563012 — Re: [PATCH v1] tty: serial: 8250: 8250_gsc:- Handle return NULL error from ioremap_nocache

On Thu, Jan 19, 2017 at 10:00 AM, Arvind Yadav
<arvind.yadav.cs@gmail.com> wrote:
> Here, If ioremap_nocache will fail. It will return NULL.
> Kernel can run into a NULL-pointer dereference.
> This error check will avoid NULL pointer dereference.

>         uart.port.mapbase       = address;
>         uart.port.membase       = ioremap_nocache(address, 16);
> +       if (!uart.port.membase) {
> +               dev_warn(&dev->dev, "Failed to map memory\n");
> +               return -ENOMEM;
> +       }

You also may do something like

void __iomem *base;
...

base = ioremap_nocache(...);
if (!base)
 return -ENOMEM;
// I doubt the message is useful, up to you

memset(&uart, 0, sizeof(uart));
...
uart.port.membase       = base;

-- 
With Best Regards,
Andy Shevchenko

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