LinuxTV Patchwork media: renesas-ceu: fix a potential NULL pointer dereference

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Submitter Kangjie Lu
Date March 9, 2019, 7:14 a.m.
Message ID <20190309071424.3600-1-kjlu@umn.edu>
Download mbox | patch
Permalink /patch/54981/
State New
Delegated to: Hans Verkuil
Headers show

Comments

Kangjie Lu - March 9, 2019, 7:14 a.m.
In case of_match_device cannot find a match, the check returns
-EINVAL to avoid a potential NULL pointer dereference

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/media/platform/renesas-ceu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
jacopo@jmondi.org - March 9, 2019, 9:58 a.m.
Hi Kangjie,
   thanks for the patch.

On Sat, Mar 09, 2019 at 01:14:24AM -0600, Kangjie Lu wrote:
> In case of_match_device cannot find a match, the check returns
> -EINVAL to avoid a potential NULL pointer dereference
>
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> ---
>  drivers/media/platform/renesas-ceu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/renesas-ceu.c b/drivers/media/platform/renesas-ceu.c
> index 150196f7cf96..4aa807c0b6c7 100644
> --- a/drivers/media/platform/renesas-ceu.c
> +++ b/drivers/media/platform/renesas-ceu.c
> @@ -1682,7 +1682,10 @@ static int ceu_probe(struct platform_device *pdev)
>
>  	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
>  		ceu_data = of_match_device(ceu_of_match, dev)->data;
> -		num_subdevs = ceu_parse_dt(ceudev);
> +		if (unlikely(!ceu_data))
> +			num_subdevs = -EINVAL;
> +		else
> +			num_subdevs = ceu_parse_dt(ceudev);

I don't think this fix is required to be honest.

If we call of_match_device() here we're sure CONFIG_OF is enabled, and
if the driver probed, so a matching compatible string has proved to
exist.

Furthermore, if you want to protect against of_match_device()
returning a NULL pointer, you should change this line first, as it
would dereference an invalid pointer:

  		ceu_data = of_match_device(ceu_of_match, dev)->data;

but again, I don't think this might happen.

Thanks
   j

>  	} else if (dev->platform_data) {
>  		/* Assume SH4 if booting with platform data. */
>  		ceu_data = &ceu_data_sh4;
> --
> 2.17.1
>

Patch

diff --git a/drivers/media/platform/renesas-ceu.c b/drivers/media/platform/renesas-ceu.c
index 150196f7cf96..4aa807c0b6c7 100644
--- a/drivers/media/platform/renesas-ceu.c
+++ b/drivers/media/platform/renesas-ceu.c
@@ -1682,7 +1682,10 @@  static int ceu_probe(struct platform_device *pdev)
 
 	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
 		ceu_data = of_match_device(ceu_of_match, dev)->data;
-		num_subdevs = ceu_parse_dt(ceudev);
+		if (unlikely(!ceu_data))
+			num_subdevs = -EINVAL;
+		else
+			num_subdevs = ceu_parse_dt(ceudev);
 	} else if (dev->platform_data) {
 		/* Assume SH4 if booting with platform data. */
 		ceu_data = &ceu_data_sh4;

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