[PATCH] drm/imx: fix memory leak in imx_pd_bind

[PATCH] drm/imx: fix memory leak in imx_pd_bind

[Navid Emamdoost]

In imx_pd_bind, the duplicated memory for imxpd->edid via kmemdup should
be released in drm_of_find_panel_or_bridge or imx_pd_register fail.

Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
Fixes: 19022aaae677 ("staging: drm/imx: Add parallel display support")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 drivers/gpu/drm/imx/parallel-display.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
index e7ce17503ae1..9522d2cb0ad5 100644
--- a/drivers/gpu/drm/imx/parallel-display.c
+++ b/drivers/gpu/drm/imx/parallel-display.c
@@ -227,14 +227,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 
 	/* port@1 is the output port */
 	ret = drm_of_find_panel_or_bridge(np, 1, 0, &imxpd->panel, &imxpd->bridge);
-	if (ret && ret != -ENODEV)
+	if (ret && ret != -ENODEV) {
+		kfree(imxpd->edid);
 		return ret;
+	}
 
 	imxpd->dev = dev;
 
 	ret = imx_pd_register(drm, imxpd);
-	if (ret)
+	if (ret) {
+		kfree(imxpd->edid);
 		return ret;
+	}
 
 	dev_set_drvdata(dev, imxpd);
 
-- 
2.17.1

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Markus Elfring]

> In imx_pd_bind, the duplicated memory for imxpd->edid via kmemdup should
> be released in drm_of_find_panel_or_bridge or imx_pd_register fail.

Please improve this change description.


> +++ b/drivers/gpu/drm/imx/parallel-display.c
> @@ -227,14 +227,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
>
>  	/* port@1 is the output port */
>  	ret = drm_of_find_panel_or_bridge(np, 1, 0, &imxpd->panel, &imxpd->bridge);
> -	if (ret && ret != -ENODEV)
> +	if (ret && ret != -ENODEV) {
> +		kfree(imxpd->edid);
>  		return ret;
> +	}
>
>  	imxpd->dev = dev;

Please use a jump target here instead of adding duplicate source code
for the completion of exception handling.

 	if (ret && ret != -ENODEV)
-		return ret;
+		goto free_edid;

…

+free_edid:
+ 	kfree(imxpd->edid);
+ 	return ret;


Regards,
Markus

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Markus Elfring]

> +free_edid:
> + 	kfree(imxpd->edid);
> + 	return ret;

I have taken another look at this change idea.
Can the function call “devm_kfree(dev, imxpd)” become relevant
also at this place?

Would you like to combine it with the update suggestion
“Fix error handling for a kmemdup() call in imx_pd_bind()”?
https://lore.kernel.org/r/3fd6aa8b-2529-7ff5-3e19-05267101b2a4@web.de/
https://lore.kernel.org/patchwork/patch/1138912/
https://lkml.org/lkml/2019/10/12/87

Regards,
Markus

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Navid Emamdoost]

No, that is not correct! You should not try to free imxpd here as it
is a resource-managed allocation via devm_kzalloc(). It means memory
allocated with this function is automatically freed on driver detach.
So, this patch introduces a double-free.

On Sat, Oct 12, 2019 at 6:54 AM Markus Elfring <Markus.Elfring@web.de> wrote:
>
> > +free_edid:
> > +     kfree(imxpd->edid);
> > +     return ret;
>
> I have taken another look at this change idea.
> Can the function call “devm_kfree(dev, imxpd)” become relevant
> also at this place?
>
> Would you like to combine it with the update suggestion
> “Fix error handling for a kmemdup() call in imx_pd_bind()”?
> https://lore.kernel.org/r/3fd6aa8b-2529-7ff5-3e19-05267101b2a4@web.de/
> https://lore.kernel.org/patchwork/patch/1138912/
> https://lkml.org/lkml/2019/10/12/87
>
> Regards,
> Markus



-- 
Navid.

Re: drm/imx: Checking a kmemdup() call in imx_pd_bind()

[Markus Elfring]

I have taken another look also at the implementation of the function “imx_pd_bind”.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/imx/parallel-display.c?id=43b815c6a8e7dbccb5b8bd9c4b099c24bc22d135#n197
https://elixir.bootlin.com/linux/v5.4-rc1/source/drivers/gpu/drm/imx/parallel-display.c#L197

Now I find an unchecked call of the function “kmemdup” suspicious.
Will this detail trigger further software development considerations?

Regards,
Markus

Re: drm/imx: Checking a kmemdup() call in imx_pd_bind()

[Navid Emamdoost]

Hi Markus,

I agree with you, kmemdup may fail so a null check seems necessary there.

On Sun, Oct 6, 2019 at 4:33 AM Markus Elfring <Markus.Elfring@web.de> wrote:
>
> I have taken another look also at the implementation of the function “imx_pd_bind”.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/imx/parallel-display.c?id=43b815c6a8e7dbccb5b8bd9c4b099c24bc22d135#n197
> https://elixir.bootlin.com/linux/v5.4-rc1/source/drivers/gpu/drm/imx/parallel-display.c#L197
>
> Now I find an unchecked call of the function “kmemdup” suspicious.
> Will this detail trigger further software development considerations?
>
> Regards,
> Markus



-- 
Navid.

Re: drm/imx: Checking a kmemdup() call in imx_pd_bind()

[Markus Elfring]

> I agree with you, kmemdup may fail so a null check seems necessary there.

Would this place (and similar ones) be pointed out for further considerations
also by the source code analysis tool which your software research group
seems to be developing?
https://github.com/umnsec/cheq/

Regards,
Markus

[PATCH 0/2] drm/imx: Adjustments for two functions

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 12 Oct 2019 10:45:45 +0200

Two update suggestions were taken into account
from static source code analysis.

Markus Elfring (2):
  Fix error handling for a kmemdup() call in imx_pd_bind()
  Fix error handling for a kmemdup() call in imx_ldb_panel_ddc()

 drivers/gpu/drm/imx/imx-ldb.c          | 2 ++
 drivers/gpu/drm/imx/parallel-display.c | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

--
2.23.0

[PATCH 1/2] drm/imx: Fix error handling for a kmemdup() call in imx_pd_bind()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 12 Oct 2019 10:30:21 +0200

The return value from a call of the function “kmemdup” was not checked
in this function implementation. Thus add the corresponding error handling.

Fixes: 19022aaae677dfa171a719e9d1ff04823ce65a65 ("staging: drm/imx: Add parallel display support")
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/gpu/drm/imx/parallel-display.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
index 35518e5de356..39c4798f56b6 100644
--- a/drivers/gpu/drm/imx/parallel-display.c
+++ b/drivers/gpu/drm/imx/parallel-display.c
@@ -210,8 +210,13 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 		return -ENOMEM;

 	edidp = of_get_property(np, "edid", &imxpd->edid_len);
-	if (edidp)
+	if (edidp) {
 		imxpd->edid = kmemdup(edidp, imxpd->edid_len, GFP_KERNEL);
+		if (!imxpd->edid) {
+			devm_kfree(dev, imxpd);
+			return -ENOMEM;
+		}
+	}

 	ret = of_property_read_string(np, "interface-pix-fmt", &fmt);
 	if (!ret) {
--
2.23.0

Re: [PATCH 1/2] drm/imx: Fix error handling for a kmemdup() call in imx_pd_bind()

[Navid Emamdoost]

On Sat, Oct 12, 2019 at 4:07 AM Markus Elfring <Markus.Elfring@web.de> wrote:
>
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sat, 12 Oct 2019 10:30:21 +0200
>
> The return value from a call of the function “kmemdup” was not checked
> in this function implementation. Thus add the corresponding error handling.
>
> Fixes: 19022aaae677dfa171a719e9d1ff04823ce65a65 ("staging: drm/imx: Add parallel display support")
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/gpu/drm/imx/parallel-display.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> index 35518e5de356..39c4798f56b6 100644
> --- a/drivers/gpu/drm/imx/parallel-display.c
> +++ b/drivers/gpu/drm/imx/parallel-display.c
> @@ -210,8 +210,13 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
>                 return -ENOMEM;
>
>         edidp = of_get_property(np, "edid", &imxpd->edid_len);
> -       if (edidp)
> +       if (edidp) {
>                 imxpd->edid = kmemdup(edidp, imxpd->edid_len, GFP_KERNEL);
> +               if (!imxpd->edid) {
> +                       devm_kfree(dev, imxpd);

You should not try to free imxpd here as it is a resource-managed
allocation via devm_kzalloc(). It means memory allocated with this
function is
 automatically freed on driver detach. So, this patch introduces a double-free.

> +                       return -ENOMEM;
> +               }
> +       }
>
>         ret = of_property_read_string(np, "interface-pix-fmt", &fmt);
>         if (!ret) {
> --
> 2.23.0
>


-- 
Navid.

Re: [PATCH 1/2] drm/imx: Fix error handling for a kmemdup() call in imx_pd_bind()

[Julia Lawall]

[-- Attachment #1: Type: text/plain, Size: 2017 bytes --]



On Sat, 12 Oct 2019, Navid Emamdoost wrote:

> On Sat, Oct 12, 2019 at 4:07 AM Markus Elfring <Markus.Elfring@web.de> wrote:
> >
> > From: Markus Elfring <elfring@users.sourceforge.net>
> > Date: Sat, 12 Oct 2019 10:30:21 +0200
> >
> > The return value from a call of the function “kmemdup” was not checked
> > in this function implementation. Thus add the corresponding error handling.
> >
> > Fixes: 19022aaae677dfa171a719e9d1ff04823ce65a65 ("staging: drm/imx: Add parallel display support")
> > Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> > ---
> >  drivers/gpu/drm/imx/parallel-display.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> > index 35518e5de356..39c4798f56b6 100644
> > --- a/drivers/gpu/drm/imx/parallel-display.c
> > +++ b/drivers/gpu/drm/imx/parallel-display.c
> > @@ -210,8 +210,13 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
> >                 return -ENOMEM;
> >
> >         edidp = of_get_property(np, "edid", &imxpd->edid_len);
> > -       if (edidp)
> > +       if (edidp) {
> >                 imxpd->edid = kmemdup(edidp, imxpd->edid_len, GFP_KERNEL);
> > +               if (!imxpd->edid) {
> > +                       devm_kfree(dev, imxpd);
>
> You should not try to free imxpd here as it is a resource-managed
> allocation via devm_kzalloc(). It means memory allocated with this
> function is
>  automatically freed on driver detach. So, this patch introduces a double-free.

No, it's not double freed since the proposed code frees it with a devm
function, removing it from the list of things to free later.  One can
wonder why the free has to be made apparent, though.

julia

>
> > +                       return -ENOMEM;
> > +               }
> > +       }
> >
> >         ret = of_property_read_string(np, "interface-pix-fmt", &fmt);
> >         if (!ret) {
> > --
> > 2.23.0
> >
>
>
> --
> Navid.
>

[PATCH 2/2] drm/imx: Fix error handling for a kmemdup() call in imx_ldb_panel_ddc()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sat, 12 Oct 2019 10:33:47 +0200

The return value from a call of the function “kmemdup” was not checked
in this function implementation. Thus add the corresponding error handling.

This issue was detected by using the Coccinelle software.

Fixes: dc80d7038883feca2abd08975165bc0d83c84762 ("drm/imx-ldb: Add support to drm-bridge")
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/gpu/drm/imx/imx-ldb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index 208069faf183..801a2265dd11 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -569,6 +569,8 @@ static int imx_ldb_panel_ddc(struct device *dev,
 			channel->edid = kmemdup(edidp,
 						channel->edid_len,
 						GFP_KERNEL);
+			if (!channel->edid)
+				return -ENOMEM;
 		} else if (!channel->panel) {
 			/* fallback to display-timings node */
 			ret = of_get_drm_display_mode(child,
--
2.23.0

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Navid Emamdoost]

On Fri, Oct 4, 2019 at 2:09 PM Navid Emamdoost
<navid.emamdoost@gmail.com> wrote:
>
> In imx_pd_bind, the duplicated memory for imxpd->edid via kmemdup should
> be released in drm_of_find_panel_or_bridge or imx_pd_register fail.
>
> Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
> Fixes: 19022aaae677 ("staging: drm/imx: Add parallel display support")
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> ---

Would you please review this patch?

Thanks,

>  drivers/gpu/drm/imx/parallel-display.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> index e7ce17503ae1..9522d2cb0ad5 100644
> --- a/drivers/gpu/drm/imx/parallel-display.c
> +++ b/drivers/gpu/drm/imx/parallel-display.c
> @@ -227,14 +227,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
>
>         /* port@1 is the output port */
>         ret = drm_of_find_panel_or_bridge(np, 1, 0, &imxpd->panel, &imxpd->bridge);
> -       if (ret && ret != -ENODEV)
> +       if (ret && ret != -ENODEV) {
> +               kfree(imxpd->edid);
>                 return ret;
> +       }
>
>         imxpd->dev = dev;
>
>         ret = imx_pd_register(drm, imxpd);
> -       if (ret)
> +       if (ret) {
> +               kfree(imxpd->edid);
>                 return ret;
> +       }
>
>         dev_set_drvdata(dev, imxpd);
>
> --
> 2.17.1
>


-- 
Navid.

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Marco Felsch]

Hi Navid,

On 19-11-21 12:31, Navid Emamdoost wrote:
> On Fri, Oct 4, 2019 at 2:09 PM Navid Emamdoost
> <navid.emamdoost@gmail.com> wrote:
> >
> > In imx_pd_bind, the duplicated memory for imxpd->edid via kmemdup should
> > be released in drm_of_find_panel_or_bridge or imx_pd_register fail.
> >
> > Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
> > Fixes: 19022aaae677 ("staging: drm/imx: Add parallel display support")
> > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> > ---
> 
> Would you please review this patch?
> 
> Thanks,

I currently work on the drm/imx driver(s) to avoid errors like [1].
Hopefully I have a working version till next week. There I fixed this
issue by using the devm_kmemdup() and dropped the explicit kfree()
within unbind().

[1] https://www.spinics.net/lists/dri-devel/msg189388.html

Regards,
  Marco

> 
> >  drivers/gpu/drm/imx/parallel-display.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> > index e7ce17503ae1..9522d2cb0ad5 100644
> > --- a/drivers/gpu/drm/imx/parallel-display.c
> > +++ b/drivers/gpu/drm/imx/parallel-display.c
> > @@ -227,14 +227,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
> >
> >         /* port@1 is the output port */
> >         ret = drm_of_find_panel_or_bridge(np, 1, 0, &imxpd->panel, &imxpd->bridge);
> > -       if (ret && ret != -ENODEV)
> > +       if (ret && ret != -ENODEV) {
> > +               kfree(imxpd->edid);
> >                 return ret;
> > +       }
> >
> >         imxpd->dev = dev;
> >
> >         ret = imx_pd_register(drm, imxpd);
> > -       if (ret)
> > +       if (ret) {
> > +               kfree(imxpd->edid);
> >                 return ret;
> > +       }
> >
> >         dev_set_drvdata(dev, imxpd);
> >
> > --
> > 2.17.1
> >
> 
> 
> -- 
> Navid.
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH] drm/imx: fix memory leak in imx_pd_bind

[Navid Emamdoost]

Thanks for the update.

On Fri, Nov 22, 2019 at 1:22 AM Marco Felsch <m.felsch@pengutronix.de> wrote:
>
> Hi Navid,
>
> On 19-11-21 12:31, Navid Emamdoost wrote:
> > On Fri, Oct 4, 2019 at 2:09 PM Navid Emamdoost
> > <navid.emamdoost@gmail.com> wrote:
> > >
> > > In imx_pd_bind, the duplicated memory for imxpd->edid via kmemdup should
> > > be released in drm_of_find_panel_or_bridge or imx_pd_register fail.
> > >
> > > Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
> > > Fixes: 19022aaae677 ("staging: drm/imx: Add parallel display support")
> > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> > > ---
> >
> > Would you please review this patch?
> >
> > Thanks,
>
> I currently work on the drm/imx driver(s) to avoid errors like [1].
> Hopefully I have a working version till next week. There I fixed this
> issue by using the devm_kmemdup() and dropped the explicit kfree()
> within unbind().
>
> [1] https://www.spinics.net/lists/dri-devel/msg189388.html
>
> Regards,
>   Marco
>
> >
> > >  drivers/gpu/drm/imx/parallel-display.c | 8 ++++++--
> > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
> > > index e7ce17503ae1..9522d2cb0ad5 100644
> > > --- a/drivers/gpu/drm/imx/parallel-display.c
> > > +++ b/drivers/gpu/drm/imx/parallel-display.c
> > > @@ -227,14 +227,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
> > >
> > >         /* port@1 is the output port */
> > >         ret = drm_of_find_panel_or_bridge(np, 1, 0, &imxpd->panel, &imxpd->bridge);
> > > -       if (ret && ret != -ENODEV)
> > > +       if (ret && ret != -ENODEV) {
> > > +               kfree(imxpd->edid);
> > >                 return ret;
> > > +       }
> > >
> > >         imxpd->dev = dev;
> > >
> > >         ret = imx_pd_register(drm, imxpd);
> > > -       if (ret)
> > > +       if (ret) {
> > > +               kfree(imxpd->edid);
> > >                 return ret;
> > > +       }
> > >
> > >         dev_set_drvdata(dev, imxpd);
> > >
> > > --
> > > 2.17.1
> > >
> >
> >
> > --
> > Navid.
> >
> >
>
> --
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |



-- 
Navid.