[PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Sakari Ailus]

What the IMGU driver did was that it first acquired the pointers to active
and try V4L2 subdev state, and only then figured out which one to use.

The problem with that approach and a later patch (see Fixes: tag) is that
as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
now an attempt to dereference that.

Fix this.

Also rewrap lines a little.

Fixes: 0d346d2a6f54 ("media: v4l2-subdev: add subdev-wide state struct")
Cc: stable@vger.kernel.org # for v5.14 and later
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/staging/media/ipu3/ipu3-v4l2.c | 31 ++++++++++++--------------
 1 file changed, 14 insertions(+), 17 deletions(-)

diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
index d1c539cefba87..2234bb8d48b34 100644
--- a/drivers/staging/media/ipu3/ipu3-v4l2.c
+++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
@@ -192,33 +192,30 @@ static int imgu_subdev_get_selection(struct v4l2_subdev *sd,
 				     struct v4l2_subdev_state *sd_state,
 				     struct v4l2_subdev_selection *sel)
 {
-	struct v4l2_rect *try_sel, *r;
-	struct imgu_v4l2_subdev *imgu_sd = container_of(sd,
-							struct imgu_v4l2_subdev,
-							subdev);
+	struct imgu_v4l2_subdev *imgu_sd =
+		container_of(sd, struct imgu_v4l2_subdev, subdev);
 
 	if (sel->pad != IMGU_NODE_IN)
 		return -EINVAL;
 
 	switch (sel->target) {
 	case V4L2_SEL_TGT_CROP:
-		try_sel = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
-		r = &imgu_sd->rect.eff;
-		break;
+		if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
+			sel->r = *v4l2_subdev_get_try_crop(sd, sd_state,
+							   sel->pad);
+		else
+			sel->r = imgu_sd->rect.eff;
+		return 0;
 	case V4L2_SEL_TGT_COMPOSE:
-		try_sel = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
-		r = &imgu_sd->rect.bds;
-		break;
+		if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
+			sel->r = *v4l2_subdev_get_try_compose(sd, sd_state,
+							      sel->pad);
+		else
+			sel->r = imgu_sd->rect.bds;
+		return 0;
 	default:
 		return -EINVAL;
 	}
-
-	if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
-		sel->r = *try_sel;
-	else
-		sel->r = *r;
-
-	return 0;
 }
 
 static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
-- 
2.30.2

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Bingbu Cao]

Sakari, 

Thanks for your patch, does it make sense that prevent the
NULL deference and throw warning in v4l2-subdev API? Though it
is the responsibility of driver to keep it safe.


Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>



On 8/26/22 3:03 AM, Sakari Ailus wrote:
> What the IMGU driver did was that it first acquired the pointers to active
> and try V4L2 subdev state, and only then figured out which one to use.
> 
> The problem with that approach and a later patch (see Fixes: tag) is that
> as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
> now an attempt to dereference that.
> 
> Fix this.
> 
> Also rewrap lines a little.
> 
> Fixes: 0d346d2a6f54 ("media: v4l2-subdev: add subdev-wide state struct")
> Cc: stable@vger.kernel.org # for v5.14 and later
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/staging/media/ipu3/ipu3-v4l2.c | 31 ++++++++++++--------------
>  1 file changed, 14 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
> index d1c539cefba87..2234bb8d48b34 100644
> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
> @@ -192,33 +192,30 @@ static int imgu_subdev_get_selection(struct v4l2_subdev *sd,
>  				     struct v4l2_subdev_state *sd_state,
>  				     struct v4l2_subdev_selection *sel)
>  {
> -	struct v4l2_rect *try_sel, *r;
> -	struct imgu_v4l2_subdev *imgu_sd = container_of(sd,
> -							struct imgu_v4l2_subdev,
> -							subdev);
> +	struct imgu_v4l2_subdev *imgu_sd =
> +		container_of(sd, struct imgu_v4l2_subdev, subdev);
>  
>  	if (sel->pad != IMGU_NODE_IN)
>  		return -EINVAL;
>  
>  	switch (sel->target) {
>  	case V4L2_SEL_TGT_CROP:
> -		try_sel = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
> -		r = &imgu_sd->rect.eff;
> -		break;
> +		if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> +			sel->r = *v4l2_subdev_get_try_crop(sd, sd_state,
> +							   sel->pad);
> +		else
> +			sel->r = imgu_sd->rect.eff;
> +		return 0;
>  	case V4L2_SEL_TGT_COMPOSE:
> -		try_sel = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
> -		r = &imgu_sd->rect.bds;
> -		break;
> +		if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> +			sel->r = *v4l2_subdev_get_try_compose(sd, sd_state,
> +							      sel->pad);
> +		else
> +			sel->r = imgu_sd->rect.bds;
> +		return 0;
>  	default:
>  		return -EINVAL;
>  	}
> -
> -	if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> -		sel->r = *try_sel;
> -	else
> -		sel->r = *r;
> -
> -	return 0;
>  }
>  
>  static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
> 

-- 
Best regards,
Bingbu Cao

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Maximilian Luz]

Hi,

On Thu, 25 Aug 2022 22:03:51 +0300, Sakari Ailus  wrote:
> What the IMGU driver did was that it first acquired the pointers to active
> and try V4L2 subdev state, and only then figured out which one to use.
> 
> The problem with that approach and a later patch (see Fixes: tag) is that
> as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
> now an attempt to dereference that.
> 
> Fix this.

Thank you for this fix, this however only addresses
imgu_subdev_get_selection(), but the issue is also present in
imgu_subdev_set_selection(). I assume that a similar fix is needed for that.
I've added a diff for that below. Feel free to squash that into your patch or
let me know if I should submit this separately.

Regards,
Max

---
  drivers/staging/media/ipu3/ipu3-v4l2.c | 25 ++++++++++++-------------
  1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
index 2234bb8d48b3..079f2635c70d 100644
--- a/drivers/staging/media/ipu3/ipu3-v4l2.c
+++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
@@ -223,10 +223,9 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_selection *sel)
  {
         struct imgu_device *imgu = v4l2_get_subdevdata(sd);
-       struct imgu_v4l2_subdev *imgu_sd = container_of(sd,
-                                                       struct imgu_v4l2_subdev,
-                                                       subdev);
-       struct v4l2_rect *rect, *try_sel;
+       struct imgu_v4l2_subdev *imgu_sd =
+               container_of(sd, struct imgu_v4l2_subdev, subdev);
+       struct v4l2_rect *rect;

         dev_dbg(&imgu->pci_dev->dev,
                  "set subdev %u sel which %u target 0x%4x rect [%ux%u]",
@@ -238,22 +237,22 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,

         switch (sel->target) {
         case V4L2_SEL_TGT_CROP:
-               try_sel = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
-               rect = &imgu_sd->rect.eff;
+               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
+                       rect = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
+               else
+                       rect = &imgu_sd->rect.eff;
                 break;
         case V4L2_SEL_TGT_COMPOSE:
-               try_sel = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
-               rect = &imgu_sd->rect.bds;
+               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
+                       rect = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
+               else
+                       rect = &imgu_sd->rect.bds;
                 break;
         default:
                 return -EINVAL;
         }

-       if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
-               *try_sel = sel->r;
-       else
-               *rect = sel->r;
-
+       *rect = sel->r;
         return 0;
  }

--
2.37.3

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Laurent Pinchart]

Hi Max,

On Wed, Sep 07, 2022 at 03:44:44PM +0200, Maximilian Luz wrote:
> On Thu, 25 Aug 2022 22:03:51 +0300, Sakari Ailus  wrote:
> > What the IMGU driver did was that it first acquired the pointers to active
> > and try V4L2 subdev state, and only then figured out which one to use.
> > 
> > The problem with that approach and a later patch (see Fixes: tag) is that
> > as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
> > now an attempt to dereference that.
> > 
> > Fix this.
> 
> Thank you for this fix, this however only addresses
> imgu_subdev_get_selection(), but the issue is also present in
> imgu_subdev_set_selection(). I assume that a similar fix is needed for that.
> I've added a diff for that below. Feel free to squash that into your patch or
> let me know if I should submit this separately.

This looks like a problem indeed. I'll let Sakari decide what he wants
to do. Adding wrappers along the lines of

static struct v4l2_rect *
imgu_subdev_get_crop(struct imgu_v4l2_subdev *sd,
		     struct v4l2_subdev_state *sd_state, unsigned int pad,
		     enum v4l2_subdev_format_whence which)
{
	if (which == V4L2_SUBDEV_FORMAT_TRY)
		return v4l2_subdev_get_try_crop(&imgu_sd->subdev, sd_state, pad);
	else
		return &imgu_sd->rect.eff;
}

(same for the selection rectangle) and using them through the code may
help.

> ---
>   drivers/staging/media/ipu3/ipu3-v4l2.c | 25 ++++++++++++-------------
>   1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
> index 2234bb8d48b3..079f2635c70d 100644
> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
> @@ -223,10 +223,9 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
>                                       struct v4l2_subdev_selection *sel)
>   {
>          struct imgu_device *imgu = v4l2_get_subdevdata(sd);
> -       struct imgu_v4l2_subdev *imgu_sd = container_of(sd,
> -                                                       struct imgu_v4l2_subdev,
> -                                                       subdev);
> -       struct v4l2_rect *rect, *try_sel;
> +       struct imgu_v4l2_subdev *imgu_sd =
> +               container_of(sd, struct imgu_v4l2_subdev, subdev);
> +       struct v4l2_rect *rect;
> 
>          dev_dbg(&imgu->pci_dev->dev,
>                   "set subdev %u sel which %u target 0x%4x rect [%ux%u]",
> @@ -238,22 +237,22 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
> 
>          switch (sel->target) {
>          case V4L2_SEL_TGT_CROP:
> -               try_sel = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
> -               rect = &imgu_sd->rect.eff;
> +               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> +                       rect = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
> +               else
> +                       rect = &imgu_sd->rect.eff;
>                  break;
>          case V4L2_SEL_TGT_COMPOSE:
> -               try_sel = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
> -               rect = &imgu_sd->rect.bds;
> +               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> +                       rect = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
> +               else
> +                       rect = &imgu_sd->rect.bds;
>                  break;
>          default:
>                  return -EINVAL;
>          }
> 
> -       if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
> -               *try_sel = sel->r;
> -       else
> -               *rect = sel->r;
> -
> +       *rect = sel->r;
>          return 0;
>   }
> 

-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Maximilian Luz]

Hi,

On 9/7/22 21:09, Laurent Pinchart wrote:
> Hi Max,
> 
> On Wed, Sep 07, 2022 at 03:44:44PM +0200, Maximilian Luz wrote:
>> On Thu, 25 Aug 2022 22:03:51 +0300, Sakari Ailus  wrote:
>>> What the IMGU driver did was that it first acquired the pointers to active
>>> and try V4L2 subdev state, and only then figured out which one to use.
>>>
>>> The problem with that approach and a later patch (see Fixes: tag) is that
>>> as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
>>> now an attempt to dereference that.
>>>
>>> Fix this.
>>
>> Thank you for this fix, this however only addresses
>> imgu_subdev_get_selection(), but the issue is also present in
>> imgu_subdev_set_selection(). I assume that a similar fix is needed for that.
>> I've added a diff for that below. Feel free to squash that into your patch or
>> let me know if I should submit this separately.
> 
> This looks like a problem indeed. I'll let Sakari decide what he wants
> to do. Adding wrappers along the lines of
> 
> static struct v4l2_rect *
> imgu_subdev_get_crop(struct imgu_v4l2_subdev *sd,
> 		     struct v4l2_subdev_state *sd_state, unsigned int pad,
> 		     enum v4l2_subdev_format_whence which)
> {
> 	if (which == V4L2_SUBDEV_FORMAT_TRY)
> 		return v4l2_subdev_get_try_crop(&imgu_sd->subdev, sd_state, pad);
> 	else
> 		return &imgu_sd->rect.eff;
> }
> 
> (same for the selection rectangle) and using them through the code may
> help.

Thanks! That does seem a good idea. I'll include those in the patch.

Regards,
Max

> 
>> ---
>>    drivers/staging/media/ipu3/ipu3-v4l2.c | 25 ++++++++++++-------------
>>    1 file changed, 12 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
>> index 2234bb8d48b3..079f2635c70d 100644
>> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
>> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
>> @@ -223,10 +223,9 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
>>                                        struct v4l2_subdev_selection *sel)
>>    {
>>           struct imgu_device *imgu = v4l2_get_subdevdata(sd);
>> -       struct imgu_v4l2_subdev *imgu_sd = container_of(sd,
>> -                                                       struct imgu_v4l2_subdev,
>> -                                                       subdev);
>> -       struct v4l2_rect *rect, *try_sel;
>> +       struct imgu_v4l2_subdev *imgu_sd =
>> +               container_of(sd, struct imgu_v4l2_subdev, subdev);
>> +       struct v4l2_rect *rect;
>>
>>           dev_dbg(&imgu->pci_dev->dev,
>>                    "set subdev %u sel which %u target 0x%4x rect [%ux%u]",
>> @@ -238,22 +237,22 @@ static int imgu_subdev_set_selection(struct v4l2_subdev *sd,
>>
>>           switch (sel->target) {
>>           case V4L2_SEL_TGT_CROP:
>> -               try_sel = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
>> -               rect = &imgu_sd->rect.eff;
>> +               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
>> +                       rect = v4l2_subdev_get_try_crop(sd, sd_state, sel->pad);
>> +               else
>> +                       rect = &imgu_sd->rect.eff;
>>                   break;
>>           case V4L2_SEL_TGT_COMPOSE:
>> -               try_sel = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
>> -               rect = &imgu_sd->rect.bds;
>> +               if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
>> +                       rect = v4l2_subdev_get_try_compose(sd, sd_state, sel->pad);
>> +               else
>> +                       rect = &imgu_sd->rect.bds;
>>                   break;
>>           default:
>>                   return -EINVAL;
>>           }
>>
>> -       if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
>> -               *try_sel = sel->r;
>> -       else
>> -               *rect = sel->r;
>> -
>> +       *rect = sel->r;
>>           return 0;
>>    }
>>
> 

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Sakari Ailus]

Hi Maximilian,

On Wed, Sep 07, 2022 at 03:44:44PM +0200, Maximilian Luz wrote:
> Hi,
> 
> On Thu, 25 Aug 2022 22:03:51 +0300, Sakari Ailus  wrote:
> > What the IMGU driver did was that it first acquired the pointers to active
> > and try V4L2 subdev state, and only then figured out which one to use.
> > 
> > The problem with that approach and a later patch (see Fixes: tag) is that
> > as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
> > now an attempt to dereference that.
> > 
> > Fix this.
> 
> Thank you for this fix, this however only addresses
> imgu_subdev_get_selection(), but the issue is also present in
> imgu_subdev_set_selection(). I assume that a similar fix is needed for that.
> I've added a diff for that below. Feel free to squash that into your patch or
> let me know if I should submit this separately.

I've already sent a PR that includes it. Could you send this one as a
patch, please?

-- 
Sakari Ailus

Re: [PATCH 1/1] ipu3-imgu: Fix NULL pointer dereference in active selection access

[Maximilian Luz]

On 9/7/22 22:01, Sakari Ailus wrote:
> Hi Maximilian,
> 
> On Wed, Sep 07, 2022 at 03:44:44PM +0200, Maximilian Luz wrote:
>> Hi,
>>
>> On Thu, 25 Aug 2022 22:03:51 +0300, Sakari Ailus  wrote:
>>> What the IMGU driver did was that it first acquired the pointers to active
>>> and try V4L2 subdev state, and only then figured out which one to use.
>>>
>>> The problem with that approach and a later patch (see Fixes: tag) is that
>>> as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is
>>> now an attempt to dereference that.
>>>
>>> Fix this.
>>
>> Thank you for this fix, this however only addresses
>> imgu_subdev_get_selection(), but the issue is also present in
>> imgu_subdev_set_selection(). I assume that a similar fix is needed for that.
>> I've added a diff for that below. Feel free to squash that into your patch or
>> let me know if I should submit this separately.
> 
> I've already sent a PR that includes it. Could you send this one as a
> patch, please?

Sure, I'll do that. I'll also follow Laurent's suggestions and introduce
get_crop()/get_compose() helpers as I think that might be a bit cleaner.

Regards,
Max