2019-04-03 09:21:39

by Yannick FERTRE

Subject: [PATCH] drm/stm: ltdc: limit number of layer to avoid memory overflow

If the number of layer is greater than LTDC_MAX_LAYER, we can have
memory overflow when reading plane_fpsi[].

Signed-off-by: Yannick Fertré <[email protected]>
---
drivers/gpu/drm/stm/ltdc.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 32fd6a3..05bd4b6 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -1021,10 +1021,13 @@ static int ltdc_get_caps(struct drm_device *ddev)
struct ltdc_device *ldev = ddev->dev_private;
u32 bus_width_log2, lcr, gc2r;

- /* at least 1 layer must be managed */
+ /*
+ * at least 1 layer must be managed & the number of layers
+ * must not exceed LTDC_MAX_LAYER
+ */
lcr = reg_read(ldev->regs, LTDC_LCR);

- ldev->caps.nb_layers = max_t(int, lcr, 1);
+ ldev->caps.nb_layers = clamp((int)lcr, 1, LTDC_MAX_LAYER);

/* set data bus width */
gc2r = reg_read(ldev->regs, LTDC_GC2R);
--
2.7.4

2019-04-05 16:31:33

by Philippe Cornu

Subject: Re: [PATCH] drm/stm: ltdc: limit number of layer to avoid memory overflow

Dear Yannick,
Thank you for your patch,

Acked-by: Philippe Cornu <[email protected]>

Philippe :)

On 4/3/19 11:20 AM, Yannick Fertré wrote:
> If the number of layer is greater than LTDC_MAX_LAYER, we can have
> memory overflow when reading plane_fpsi[].
>
> Signed-off-by: Yannick Fertré <[email protected]>
> ---
> drivers/gpu/drm/stm/ltdc.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 32fd6a3..05bd4b6 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -1021,10 +1021,13 @@ static int ltdc_get_caps(struct drm_device *ddev)
> struct ltdc_device *ldev = ddev->dev_private;
> u32 bus_width_log2, lcr, gc2r;
>
> - /* at least 1 layer must be managed */
> + /*
> + * at least 1 layer must be managed & the number of layers
> + * must not exceed LTDC_MAX_LAYER
> + */
> lcr = reg_read(ldev->regs, LTDC_LCR);
>
> - ldev->caps.nb_layers = max_t(int, lcr, 1);
> + ldev->caps.nb_layers = clamp((int)lcr, 1, LTDC_MAX_LAYER);
>
> /* set data bus width */
> gc2r = reg_read(ldev->regs, LTDC_GC2R);
>

2019-04-24 12:30:14

by Benjamin Gaignard

Subject: Re: [PATCH] drm/stm: ltdc: limit number of layer to avoid memory overflow

Le ven. 5 avr. 2019 à 18:30, Philippe CORNU <[email protected]> a écrit :
>
> Dear Yannick,
> Thank you for your patch,
>
> Acked-by: Philippe Cornu <[email protected]>
>

Applied on drm-misc-next,
Thanks,
Benjamin

> Philippe :)
>
> On 4/3/19 11:20 AM, Yannick Fertré wrote:
> > If the number of layer is greater than LTDC_MAX_LAYER, we can have
> > memory overflow when reading plane_fpsi[].
> >
> > Signed-off-by: Yannick Fertré <[email protected]>
> > ---
> > drivers/gpu/drm/stm/ltdc.c | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> > index 32fd6a3..05bd4b6 100644
> > --- a/drivers/gpu/drm/stm/ltdc.c
> > +++ b/drivers/gpu/drm/stm/ltdc.c
> > @@ -1021,10 +1021,13 @@ static int ltdc_get_caps(struct drm_device *ddev)
> > struct ltdc_device *ldev = ddev->dev_private;
> > u32 bus_width_log2, lcr, gc2r;
> >
> > - /* at least 1 layer must be managed */
> > + /*
> > + * at least 1 layer must be managed & the number of layers
> > + * must not exceed LTDC_MAX_LAYER
> > + */
> > lcr = reg_read(ldev->regs, LTDC_LCR);
> >
> > - ldev->caps.nb_layers = max_t(int, lcr, 1);
> > + ldev->caps.nb_layers = clamp((int)lcr, 1, LTDC_MAX_LAYER);
> >
> > /* set data bus width */
> > gc2r = reg_read(ldev->regs, LTDC_GC2R);
> >
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