[PATCH] drm: mali-dp: potential dereference of null pointer

[PATCH] drm: mali-dp: potential dereference of null pointer

[Jiasheng Jiang]

The return value of kzalloc() needs to be checked.
To avoid use of null pointer '&state->base' in case of the
failure of alloc.

Fixes: 99665d072183 ("drm: mali-dp: add malidp_crtc_state struct")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
 drivers/gpu/drm/arm/malidp_crtc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
index 494075ddbef6..b5928b52e279 100644
--- a/drivers/gpu/drm/arm/malidp_crtc.c
+++ b/drivers/gpu/drm/arm/malidp_crtc.c
@@ -487,7 +487,10 @@ static void malidp_crtc_reset(struct drm_crtc *crtc)
 	if (crtc->state)
 		malidp_crtc_destroy_state(crtc, crtc->state);
 
-	__drm_atomic_helper_crtc_reset(crtc, &state->base);
+	if (state)
+		__drm_atomic_helper_crtc_reset(crtc, &state->base);
+	else
+		__drm_atomic_helper_crtc_reset(crtc, NULL);
 }
 
 static int malidp_crtc_enable_vblank(struct drm_crtc *crtc)
-- 
2.25.1

Re: [PATCH] drm: mali-dp: potential dereference of null pointer

[Brian Starkey]

Hi,

On Tue, Dec 14, 2021 at 06:08:37PM +0800, Jiasheng Jiang wrote:
> The return value of kzalloc() needs to be checked.
> To avoid use of null pointer '&state->base' in case of the
> failure of alloc.
> 
> Fixes: 99665d072183 ("drm: mali-dp: add malidp_crtc_state struct")
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> ---

You can add my r-b to this one too. Thanks!

>  drivers/gpu/drm/arm/malidp_crtc.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
> index 494075ddbef6..b5928b52e279 100644
> --- a/drivers/gpu/drm/arm/malidp_crtc.c
> +++ b/drivers/gpu/drm/arm/malidp_crtc.c
> @@ -487,7 +487,10 @@ static void malidp_crtc_reset(struct drm_crtc *crtc)
>  	if (crtc->state)
>  		malidp_crtc_destroy_state(crtc, crtc->state);
>  
> -	__drm_atomic_helper_crtc_reset(crtc, &state->base);
> +	if (state)
> +		__drm_atomic_helper_crtc_reset(crtc, &state->base);
> +	else
> +		__drm_atomic_helper_crtc_reset(crtc, NULL);
>  }
>  
>  static int malidp_crtc_enable_vblank(struct drm_crtc *crtc)
> -- 
> 2.25.1
> 

Re: [PATCH] drm: mali-dp: potential dereference of null pointer

[Daniel Vetter]

On Tue, Dec 14, 2021 at 11:02:02AM +0000, Brian Starkey wrote:
> Hi,
> 
> On Tue, Dec 14, 2021 at 06:08:37PM +0800, Jiasheng Jiang wrote:
> > The return value of kzalloc() needs to be checked.
> > To avoid use of null pointer '&state->base' in case of the
> > failure of alloc.
> > 
> > Fixes: 99665d072183 ("drm: mali-dp: add malidp_crtc_state struct")
> > Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
> > ---
> 
> You can add my r-b to this one too. Thanks!

Are you (or someone else from arm) also pushing these? Otherwise they'll
get lost.
-Daniel

> 
> >  drivers/gpu/drm/arm/malidp_crtc.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
> > index 494075ddbef6..b5928b52e279 100644
> > --- a/drivers/gpu/drm/arm/malidp_crtc.c
> > +++ b/drivers/gpu/drm/arm/malidp_crtc.c
> > @@ -487,7 +487,10 @@ static void malidp_crtc_reset(struct drm_crtc *crtc)
> >  	if (crtc->state)
> >  		malidp_crtc_destroy_state(crtc, crtc->state);
> >  
> > -	__drm_atomic_helper_crtc_reset(crtc, &state->base);
> > +	if (state)
> > +		__drm_atomic_helper_crtc_reset(crtc, &state->base);
> > +	else
> > +		__drm_atomic_helper_crtc_reset(crtc, NULL);
> >  }
> >  
> >  static int malidp_crtc_enable_vblank(struct drm_crtc *crtc)
> > -- 
> > 2.25.1
> > 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch