From: Zeng Jingxiang <[email protected]>
The "plane" pointer was access before checking if it was NULL.
The drm_atomic_get_old_plane_state() function will dereference
the pointer "plane".
345 struct drm_plane_state *old_plane_state =
drm_atomic_get_old_plane_state(state, plane);
346 struct drm_plane_state *new_plane_state =
drm_atomic_get_new_plane_state(state, plane);
A NULL check for "plane" indicates that it may be NULL
363 if (!plane || !new_plane_state || !old_plane_state)
Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic disable and update")
Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer")
Signed-off-by: Zeng Jingxiang <[email protected]>
---
drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c
index 2735b8eb3537..d2bc998b65ce 100644
--- a/drivers/gpu/drm/kmb/kmb_plane.c
+++ b/drivers/gpu/drm/kmb/kmb_plane.c
@@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct kmb_drm_private *kmb,
static void kmb_plane_atomic_update(struct drm_plane *plane,
struct drm_atomic_state *state)
{
- struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state,
- plane);
- struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
- plane);
+ struct drm_plane_state *old_plane_state, *new_plane_state;
struct drm_framebuffer *fb;
struct kmb_drm_private *kmb;
unsigned int width;
@@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct drm_plane *plane,
static dma_addr_t addr[MAX_SUB_PLANES];
struct disp_cfg *init_disp_cfg;
- if (!plane || !new_plane_state || !old_plane_state)
+ if (!plane)
+ return;
+
+ old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+ new_plane_state = drm_atomic_get_new_plane_state(state, plane);
+
+ if (!new_plane_state || !old_plane_state)
return;
fb = new_plane_state->fb;
--
2.27.0
Hi
Am 29.07.22 um 16:23 schrieb Thomas Zimmermann:
> Hi
>
> Am 29.07.22 um 05:07 schrieb Zeng Jingxiang:
>> From: Zeng Jingxiang <[email protected]>
>>
>> The "plane" pointer was access before checking if it was NULL.
>>
>> The drm_atomic_get_old_plane_state() function will dereference
>> the pointer "plane".
>> 345 struct drm_plane_state *old_plane_state =
>> drm_atomic_get_old_plane_state(state, plane);
>> 346 struct drm_plane_state *new_plane_state =
>> drm_atomic_get_new_plane_state(state, plane);
>>
>> A NULL check for "plane" indicates that it may be NULL
>> 363 if (!plane || !new_plane_state || !old_plane_state)
>
> Is this an actual bug that happens?
>
> All planes should always have a state. Therefore the tests for
> !new_plane_state and !old_plane_state can be removed, I'd say.
Just to clarify: moving the test for !plane before using one of the
get_plane_state functions is a correct bugfix.
Best regards
Thomas
>
> Best regards
> Thomas
>
>>
>> Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic
>> disable and update")
>> Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state
>> pointer")
>> Signed-off-by: Zeng Jingxiang <[email protected]>
>> ---
>> drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
>> 1 file changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
>> b/drivers/gpu/drm/kmb/kmb_plane.c
>> index 2735b8eb3537..d2bc998b65ce 100644
>> --- a/drivers/gpu/drm/kmb/kmb_plane.c
>> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
>> @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct
>> kmb_drm_private *kmb,
>> static void kmb_plane_atomic_update(struct drm_plane *plane,
>> struct drm_atomic_state *state)
>> {
>> - struct drm_plane_state *old_plane_state =
>> drm_atomic_get_old_plane_state(state,
>> - plane);
>> - struct drm_plane_state *new_plane_state =
>> drm_atomic_get_new_plane_state(state,
>> - plane);
>> + struct drm_plane_state *old_plane_state, *new_plane_state;
>> struct drm_framebuffer *fb;
>> struct kmb_drm_private *kmb;
>> unsigned int width;
>> @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct
>> drm_plane *plane,
>> static dma_addr_t addr[MAX_SUB_PLANES];
>> struct disp_cfg *init_disp_cfg;
>> - if (!plane || !new_plane_state || !old_plane_state)
>> + if (!plane)
>> + return;
>> +
>> + old_plane_state = drm_atomic_get_old_plane_state(state, plane);
>> + new_plane_state = drm_atomic_get_new_plane_state(state, plane);
>> +
>> + if (!new_plane_state || !old_plane_state)
>> return;
>> fb = new_plane_state->fb;
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
Hi
Am 29.07.22 um 05:07 schrieb Zeng Jingxiang:
> From: Zeng Jingxiang <[email protected]>
>
> The "plane" pointer was access before checking if it was NULL.
>
> The drm_atomic_get_old_plane_state() function will dereference
> the pointer "plane".
> 345 struct drm_plane_state *old_plane_state =
> drm_atomic_get_old_plane_state(state, plane);
> 346 struct drm_plane_state *new_plane_state =
> drm_atomic_get_new_plane_state(state, plane);
>
> A NULL check for "plane" indicates that it may be NULL
> 363 if (!plane || !new_plane_state || !old_plane_state)
Is this an actual bug that happens?
All planes should always have a state. Therefore the tests for
!new_plane_state and !old_plane_state can be removed, I'd say.
Best regards
Thomas
>
> Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic disable and update")
> Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer")
> Signed-off-by: Zeng Jingxiang <[email protected]>
> ---
> drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c
> index 2735b8eb3537..d2bc998b65ce 100644
> --- a/drivers/gpu/drm/kmb/kmb_plane.c
> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
> @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct kmb_drm_private *kmb,
> static void kmb_plane_atomic_update(struct drm_plane *plane,
> struct drm_atomic_state *state)
> {
> - struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state,
> - plane);
> - struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
> - plane);
> + struct drm_plane_state *old_plane_state, *new_plane_state;
> struct drm_framebuffer *fb;
> struct kmb_drm_private *kmb;
> unsigned int width;
> @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct drm_plane *plane,
> static dma_addr_t addr[MAX_SUB_PLANES];
> struct disp_cfg *init_disp_cfg;
>
> - if (!plane || !new_plane_state || !old_plane_state)
> + if (!plane)
> + return;
> +
> + old_plane_state = drm_atomic_get_old_plane_state(state, plane);
> + new_plane_state = drm_atomic_get_new_plane_state(state, plane);
> +
> + if (!new_plane_state || !old_plane_state)
> return;
>
> fb = new_plane_state->fb;
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
Agree with Thomas, drm_atomic_commit() will not call kmb_atomic_update() with a NULL plane. This is not an actual bug.
Thanks,
Anitha
> -----Original Message-----
> From: Thomas Zimmermann <[email protected]>
> Sent: Friday, July 29, 2022 7:26 AM
> To: Zeng Jingxiang <[email protected]>; Chrisanthus, Anitha
> <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Cc: Zeng Jingxiang <[email protected]>; [email protected];
> [email protected]
> Subject: Re: [PATCH] drm/kmb: fix dereference before NULL check in
> kmb_plane_atomic_update()
>
> Hi
>
> Am 29.07.22 um 16:23 schrieb Thomas Zimmermann:
> > Hi
> >
> > Am 29.07.22 um 05:07 schrieb Zeng Jingxiang:
> >> From: Zeng Jingxiang <[email protected]>
> >>
> >> The "plane" pointer was access before checking if it was NULL.
> >>
> >> The drm_atomic_get_old_plane_state() function will dereference
> >> the pointer "plane".
> >> 345 struct drm_plane_state *old_plane_state =
> >> drm_atomic_get_old_plane_state(state, plane);
> >> 346 struct drm_plane_state *new_plane_state =
> >> drm_atomic_get_new_plane_state(state, plane);
> >>
> >> A NULL check for "plane" indicates that it may be NULL
> >> 363 if (!plane || !new_plane_state || !old_plane_state)
> >
> > Is this an actual bug that happens?
> >
> > All planes should always have a state. Therefore the tests for
> > !new_plane_state and !old_plane_state can be removed, I'd say.
>
> Just to clarify: moving the test for !plane before using one of the
> get_plane_state functions is a correct bugfix.
>
> Best regards
> Thomas
>
> >
> > Best regards
> > Thomas
> >
> >>
> >> Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic
> >> disable and update")
> >> Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state
> >> pointer")
> >> Signed-off-by: Zeng Jingxiang <[email protected]>
> >> ---
> >> drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
> >> 1 file changed, 8 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
> >> b/drivers/gpu/drm/kmb/kmb_plane.c
> >> index 2735b8eb3537..d2bc998b65ce 100644
> >> --- a/drivers/gpu/drm/kmb/kmb_plane.c
> >> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
> >> @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct
> >> kmb_drm_private *kmb,
> >> static void kmb_plane_atomic_update(struct drm_plane *plane,
> >> struct drm_atomic_state *state)
> >> {
> >> - struct drm_plane_state *old_plane_state =
> >> drm_atomic_get_old_plane_state(state,
> >> - plane);
> >> - struct drm_plane_state *new_plane_state =
> >> drm_atomic_get_new_plane_state(state,
> >> - plane);
> >> + struct drm_plane_state *old_plane_state, *new_plane_state;
> >> struct drm_framebuffer *fb;
> >> struct kmb_drm_private *kmb;
> >> unsigned int width;
> >> @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct
> >> drm_plane *plane,
> >> static dma_addr_t addr[MAX_SUB_PLANES];
> >> struct disp_cfg *init_disp_cfg;
> >> - if (!plane || !new_plane_state || !old_plane_state)
> >> + if (!plane)
> >> + return;
> >> +
> >> + old_plane_state = drm_atomic_get_old_plane_state(state, plane);
> >> + new_plane_state = drm_atomic_get_new_plane_state(state, plane);
> >> +
> >> + if (!new_plane_state || !old_plane_state)
> >> return;
> >> fb = new_plane_state->fb;
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev
Hi
Am 29.07.22 um 18:40 schrieb Chrisanthus, Anitha:
> Agree with Thomas, drm_atomic_commit() will not call kmb_atomic_update() with a NULL plane. This is not an actual bug.
Indeed, it's the atomic_update function. I didn't notice at first.
>
> Thanks,
> Anitha
>
>> -----Original Message-----
>> From: Thomas Zimmermann <[email protected]>
>> Sent: Friday, July 29, 2022 7:26 AM
>> To: Zeng Jingxiang <[email protected]>; Chrisanthus, Anitha
>> <[email protected]>; [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]
>> Cc: Zeng Jingxiang <[email protected]>; [email protected];
>> [email protected]
>> Subject: Re: [PATCH] drm/kmb: fix dereference before NULL check in
>> kmb_plane_atomic_update()
>>
>> Hi
>>
>> Am 29.07.22 um 16:23 schrieb Thomas Zimmermann:
>>> Hi
>>>
>>> Am 29.07.22 um 05:07 schrieb Zeng Jingxiang:
>>>> From: Zeng Jingxiang <[email protected]>
>>>>
>>>> The "plane" pointer was access before checking if it was NULL.
>>>>
>>>> The drm_atomic_get_old_plane_state() function will dereference
>>>> the pointer "plane".
>>>> 345 struct drm_plane_state *old_plane_state =
>>>> drm_atomic_get_old_plane_state(state, plane);
>>>> 346 struct drm_plane_state *new_plane_state =
>>>> drm_atomic_get_new_plane_state(state, plane);
>>>>
>>>> A NULL check for "plane" indicates that it may be NULL
>>>> 363 if (!plane || !new_plane_state || !old_plane_state)
>>>
>>> Is this an actual bug that happens?
>>>
>>> All planes should always have a state. Therefore the tests for
>>> !new_plane_state and !old_plane_state can be removed, I'd say.
>>
>> Just to clarify: moving the test for !plane before using one of the
>> get_plane_state functions is a correct bugfix.
>>
>> Best regards
>> Thomas
>>
>>>
>>> Best regards
>>> Thomas
>>>
>>>>
>>>> Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic
>>>> disable and update")
>>>> Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state
>>>> pointer")
>>>> Signed-off-by: Zeng Jingxiang <[email protected]>
>>>> ---
>>>> drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
>>>> 1 file changed, 8 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
>>>> b/drivers/gpu/drm/kmb/kmb_plane.c
>>>> index 2735b8eb3537..d2bc998b65ce 100644
>>>> --- a/drivers/gpu/drm/kmb/kmb_plane.c
>>>> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
>>>> @@ -342,10 +342,7 @@ static void kmb_plane_set_alpha(struct
>>>> kmb_drm_private *kmb,
>>>> static void kmb_plane_atomic_update(struct drm_plane *plane,
>>>> struct drm_atomic_state *state)
>>>> {
>>>> - struct drm_plane_state *old_plane_state =
>>>> drm_atomic_get_old_plane_state(state,
>>>> - plane);
>>>> - struct drm_plane_state *new_plane_state =
>>>> drm_atomic_get_new_plane_state(state,
>>>> - plane);
>>>> + struct drm_plane_state *old_plane_state, *new_plane_state;
>>>> struct drm_framebuffer *fb;
>>>> struct kmb_drm_private *kmb;
>>>> unsigned int width;
>>>> @@ -360,7 +357,13 @@ static void kmb_plane_atomic_update(struct
>>>> drm_plane *plane,
>>>> static dma_addr_t addr[MAX_SUB_PLANES];
>>>> struct disp_cfg *init_disp_cfg;
>>>> - if (!plane || !new_plane_state || !old_plane_state)
>>>> + if (!plane)
>>>> + return;
>>>> +
>>>> + old_plane_state = drm_atomic_get_old_plane_state(state, plane);
>>>> + new_plane_state = drm_atomic_get_new_plane_state(state, plane);
>>>> +
>>>> + if (!new_plane_state || !old_plane_state)
To add to my previous reply, none of these variables can legally be NULL
here. If plane if NULL, DRM helpers would run atomic_disable instead.
If you want to fix anything, just remove the tests entirely and save a
few CPU cycles.
Best regards
Thomas
>>>> return;
>>>> fb = new_plane_state->fb;
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Ivo Totev
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev