[PATCH] drm/ast: 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: f0adbc382b8b ("drm/ast: Allocate initial CRTC state of the correct size")
Signed-off-by: Jiasheng Jiang 
---
 drivers/gpu/drm/ast/ast_mode.c | 5 -
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 36d9575aa27b..65099f0359f9 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1120,7 +1120,10 @@ static void ast_crtc_reset(struct drm_crtc *crtc)
if (crtc->state)
crtc->funcs->atomic_destroy_state(crtc, crtc->state);
 
-   __drm_atomic_helper_crtc_reset(crtc, _state->base);
+   if (ast_state)
+   __drm_atomic_helper_crtc_reset(crtc, _state->base);
+   else
+   __drm_atomic_helper_crtc_reset(crtc, NULL);
 }
 
 static struct drm_crtc_state *
-- 
2.25.1

Re: [PATCH] drm/ast: potential dereference of null pointer

[Thomas Zimmermann]

Hi,

thanks for the patch.

Am 13.12.21 um 06:39 schrieb Jiasheng Jiang:

he return value of kzalloc() needs to be checked.


'The'


To avoid use of null pointer '_state->base' in case of the
failure of alloc.

Fixes: f0adbc382b8b ("drm/ast: Allocate initial CRTC state of the correct size")
Signed-off-by: Jiasheng Jiang 
---
  drivers/gpu/drm/ast/ast_mode.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 36d9575aa27b..67f8e3f90ea2 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1120,7 +1120,8 @@ static void ast_crtc_reset(struct drm_crtc *crtc)
if (crtc->state)
crtc->funcs->atomic_destroy_state(crtc, crtc->state);
  
-	__drm_atomic_helper_crtc_reset(crtc, _state->base);

+   if (ast_state)
+   __drm_atomic_helper_crtc_reset(crtc, _state->base);


If ast_state is NULL, __drm_atomic_helper_crtc_reset() has to be called 
with a state of NULL. Otherwise the reset might leave the dangling 
pointer in the CRTC's state field.


Best regards
Thomas


  }
  
  static struct drm_crtc_state *




--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev


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[PATCH] drm/ast: potential dereference of null pointer

[Jiasheng Jiang]

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

Fixes: f0adbc382b8b ("drm/ast: Allocate initial CRTC state of the correct size")
Signed-off-by: Jiasheng Jiang 
---
 drivers/gpu/drm/ast/ast_mode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 36d9575aa27b..67f8e3f90ea2 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -1120,7 +1120,8 @@ static void ast_crtc_reset(struct drm_crtc *crtc)
if (crtc->state)
crtc->funcs->atomic_destroy_state(crtc, crtc->state);
 
-   __drm_atomic_helper_crtc_reset(crtc, _state->base);
+   if (ast_state)
+   __drm_atomic_helper_crtc_reset(crtc, _state->base);
 }
 
 static struct drm_crtc_state *
-- 
2.25.1