2022-04-05 00:09:13

by Miaoqian Lin

Subject: [PATCH] serial: 8250_aspeed_vuart: Fix potential NULL dereference in aspeed_vuart_probe

platform_get_resource() may fail and return NULL, so we should
better check it's return value to avoid a NULL pointer dereference.

Fixes: 54da3e381c2b ("serial: 8250_aspeed_vuart: use UPF_IOREMAP to set up register mapping")
Signed-off-by: Miaoqian Lin <[email protected]>
---
drivers/tty/serial/8250/8250_aspeed_vuart.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
index 93fe10c680fb..9d2a7856784f 100644
--- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
+++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
@@ -429,6 +429,8 @@ static int aspeed_vuart_probe(struct platform_device *pdev)
timer_setup(&vuart->unthrottle_timer, aspeed_vuart_unthrottle_exp, 0);

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -EINVAL;

memset(&port, 0, sizeof(port));
port.port.private_data = vuart;
--
2.17.1

2022-04-05 00:09:52

by Greg Kroah-Hartman

Subject: Re: [PATCH] serial: 8250_aspeed_vuart: Fix potential NULL dereference in aspeed_vuart_probe

On Mon, Apr 04, 2022 at 02:38:40PM +0000, Miaoqian Lin wrote:
> platform_get_resource() may fail and return NULL, so we should
> better check it's return value to avoid a NULL pointer dereference.
>
> Fixes: 54da3e381c2b ("serial: 8250_aspeed_vuart: use UPF_IOREMAP to set up register mapping")
> Signed-off-by: Miaoqian Lin <[email protected]>
> ---
> drivers/tty/serial/8250/8250_aspeed_vuart.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> index 93fe10c680fb..9d2a7856784f 100644
> --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
> +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> @@ -429,6 +429,8 @@ static int aspeed_vuart_probe(struct platform_device *pdev)
> timer_setup(&vuart->unthrottle_timer, aspeed_vuart_unthrottle_exp, 0);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -EINVAL;

How did you test this change was correct?

2022-04-05 03:11:08

by Miaoqian Lin

Subject: Re: [PATCH] serial: 8250_aspeed_vuart: Fix potential NULL dereference in aspeed_vuart_probe

On Mon, Apr 04, 2022 at 04:45:50PM +0200, Greg Kroah-Hartman wrote:
> On Mon, Apr 04, 2022 at 02:38:40PM +0000, Miaoqian Lin wrote:
> > platform_get_resource() may fail and return NULL, so we should
> > better check it's return value to avoid a NULL pointer dereference.
> >
> > Fixes: 54da3e381c2b ("serial: 8250_aspeed_vuart: use UPF_IOREMAP to set up register mapping")
> > Signed-off-by: Miaoqian Lin <[email protected]>
> > ---
> > drivers/tty/serial/8250/8250_aspeed_vuart.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > index 93fe10c680fb..9d2a7856784f 100644
> > --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> > @@ -429,6 +429,8 @@ static int aspeed_vuart_probe(struct platform_device *pdev)
> > timer_setup(&vuart->unthrottle_timer, aspeed_vuart_unthrottle_exp, 0);
> >
> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + if (!res)
> > + return -EINVAL;
>
> How did you test this change was correct?

Hi,

I look into the implementation of platform_get_resource(),
and do cross-check the usages of it in the codebase, especially
the usages in other probe function.
And I go through some simliar bugfix commits in the revision history——
add check for return value of platform_get_resource() in probe
functions，to learn the way to fix this kind of bugs.
But sorry I don't have the corresponding device for running test.