[PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[Noralf Trønnes]

Non-atomic drivers like ast doesn't have connector->state set resulting
in a NULL pointer deref:

[   29.609593] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
[   29.609619] Call Trace:
[   29.609630]  ? drm_helper_probe_single_connector_modes+0x27f/0x680
[   29.609640]  drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
[   29.753065]  __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
[   29.753160]  ? drm_modeset_unlock_all+0x31/0x50 [drm]
[   29.765758]  ast_fbdev_init+0xa8/0xc0 [ast]
[   29.765762]  ast_driver_load.cold.7+0x2b3/0xe11 [ast]
[   29.765775]  drm_dev_register+0x111/0x150 [drm]

Fix by bailing out if the driver does not support atomic modesetting.

Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev helper")
Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_fb_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2339f0f8f5a8..899c2eca26d1 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
 	int num_connectors_detected = 0;
 	struct drm_modeset_acquire_ctx ctx;
 
+	if (!drm_drv_uses_atomic_modeset(dev))
+		return false;
+
 	save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
 	if (!save_enabled)
 		return false;
-- 
2.20.1

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Re: [PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[Daniel Vetter]

On Tue, Apr 23, 2019 at 04:53:53PM +0200, Noralf Trønnes wrote:
> Non-atomic drivers like ast doesn't have connector->state set resulting
> in a NULL pointer deref:
> 
> [   29.609593] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> [   29.609619] Call Trace:
> [   29.609630]  ? drm_helper_probe_single_connector_modes+0x27f/0x680
> [   29.609640]  drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
> [   29.753065]  __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
> [   29.753160]  ? drm_modeset_unlock_all+0x31/0x50 [drm]
> [   29.765758]  ast_fbdev_init+0xa8/0xc0 [ast]
> [   29.765762]  ast_driver_load.cold.7+0x2b3/0xe11 [ast]
> [   29.765775]  drm_dev_register+0x111/0x150 [drm]
> 
> Fix by bailing out if the driver does not support atomic modesetting.
> 
> Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev helper")
> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/gpu/drm/drm_fb_helper.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 2339f0f8f5a8..899c2eca26d1 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
>  	int num_connectors_detected = 0;
>  	struct drm_modeset_acquire_ctx ctx;
>  
> +	if (!drm_drv_uses_atomic_modeset(dev))
> +		return false;

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

I think for merging we're already past feature freeze, but
drm-misc-next-fixes hasn't been rolled forward yet. I think you need to
wait for drm-misc maintainers to do that (I pinged them already), and then
put this one there.
-Daniel

> +
>  	save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
>  	if (!save_enabled)
>  		return false;
> -- 
> 2.20.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[Thomas Zimmermann]

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Thanks for fixing this so quickly.

Tested-by: Thomas Zimmermann <tzimmermann@suse.de>

Am 23.04.19 um 16:53 schrieb Noralf Trønnes:
> Non-atomic drivers like ast doesn't have connector->state set resulting
> in a NULL pointer deref:
> 
> [   29.609593] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> [   29.609619] Call Trace:
> [   29.609630]  ? drm_helper_probe_single_connector_modes+0x27f/0x680
> [   29.609640]  drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
> [   29.753065]  __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
> [   29.753160]  ? drm_modeset_unlock_all+0x31/0x50 [drm]
> [   29.765758]  ast_fbdev_init+0xa8/0xc0 [ast]
> [   29.765762]  ast_driver_load.cold.7+0x2b3/0xe11 [ast]
> [   29.765775]  drm_dev_register+0x111/0x150 [drm]
> 
> Fix by bailing out if the driver does not support atomic modesetting.
> 
> Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev helper")
> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/gpu/drm/drm_fb_helper.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 2339f0f8f5a8..899c2eca26d1 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
>  	int num_connectors_detected = 0;
>  	struct drm_modeset_acquire_ctx ctx;
>  
> +	if (!drm_drv_uses_atomic_modeset(dev))
> +		return false;
> +
>  	save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
>  	if (!save_enabled)
>  		return false;
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)


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[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

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Re: [PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[Noralf Trønnes]

Den 23.04.2019 21.01, skrev Daniel Vetter:
> On Tue, Apr 23, 2019 at 04:53:53PM +0200, Noralf Trønnes wrote:
>> Non-atomic drivers like ast doesn't have connector->state set resulting
>> in a NULL pointer deref:
>>
>> [   29.609593] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
>> [   29.609619] Call Trace:
>> [   29.609630]  ? drm_helper_probe_single_connector_modes+0x27f/0x680
>> [   29.609640]  drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
>> [   29.753065]  __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
>> [   29.753160]  ? drm_modeset_unlock_all+0x31/0x50 [drm]
>> [   29.765758]  ast_fbdev_init+0xa8/0xc0 [ast]
>> [   29.765762]  ast_driver_load.cold.7+0x2b3/0xe11 [ast]
>> [   29.765775]  drm_dev_register+0x111/0x150 [drm]
>>
>> Fix by bailing out if the driver does not support atomic modesetting.
>>
>> Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev helper")
>> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
>> ---
>>  drivers/gpu/drm/drm_fb_helper.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>> index 2339f0f8f5a8..899c2eca26d1 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
>>  	int num_connectors_detected = 0;
>>  	struct drm_modeset_acquire_ctx ctx;
>>  
>> +	if (!drm_drv_uses_atomic_modeset(dev))
>> +		return false;
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> I think for merging we're already past feature freeze, but
> drm-misc-next-fixes hasn't been rolled forward yet. I think you need to
> wait for drm-misc maintainers to do that (I pinged them already), and then
> put this one there.

I saw that -fixes was updated including Dave's i915 backported revert,
so I have applied this to drm-misc-next-fixes.

How/when will this show up in drm-misc-next? My drm_fb_helper
refactoring needs to be rebased on this.

Thanks,
Noralf.

> -Daniel
> 
>> +
>>  	save_enabled = kcalloc(count, sizeof(bool), GFP_KERNEL);
>>  	if (!save_enabled)
>>  		return false;
>> -- 
>> 2.20.1
>>
> 
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Re: [PATCH] drm/fb-helper: Fix drm_fb_helper_firmware_config() NULL pointer deref

[Daniel Vetter]

On Wed, Apr 24, 2019 at 4:06 PM Noralf Trønnes <noralf@tronnes.org> wrote:
>
>
>
> Den 23.04.2019 21.01, skrev Daniel Vetter:
> > On Tue, Apr 23, 2019 at 04:53:53PM +0200, Noralf Trønnes wrote:
> >> Non-atomic drivers like ast doesn't have connector->state set resulting
> >> in a NULL pointer deref:
> >>
> >> [   29.609593] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> >> [   29.609619] Call Trace:
> >> [   29.609630]  ? drm_helper_probe_single_connector_modes+0x27f/0x680
> >> [   29.609640]  drm_setup_crtcs+0x431/0xd80 [drm_kms_helper]
> >> [   29.753065]  __drm_fb_helper_initial_config_and_unlock+0x6f/0x6a0
> >> [   29.753160]  ? drm_modeset_unlock_all+0x31/0x50 [drm]
> >> [   29.765758]  ast_fbdev_init+0xa8/0xc0 [ast]
> >> [   29.765762]  ast_driver_load.cold.7+0x2b3/0xe11 [ast]
> >> [   29.765775]  drm_dev_register+0x111/0x150 [drm]
> >>
> >> Fix by bailing out if the driver does not support atomic modesetting.
> >>
> >> Fixes: 09ded8af57bc ("drm/i915/fbdev: Move intel_fb_initial_config() to fbdev helper")
> >> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> >> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> >> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> >> ---
> >>  drivers/gpu/drm/drm_fb_helper.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> >> index 2339f0f8f5a8..899c2eca26d1 100644
> >> --- a/drivers/gpu/drm/drm_fb_helper.c
> >> +++ b/drivers/gpu/drm/drm_fb_helper.c
> >> @@ -2588,6 +2588,9 @@ static bool drm_fb_helper_firmware_config(struct drm_fb_helper *fb_helper,
> >>      int num_connectors_detected = 0;
> >>      struct drm_modeset_acquire_ctx ctx;
> >>
> >> +    if (!drm_drv_uses_atomic_modeset(dev))
> >> +            return false;
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >
> > I think for merging we're already past feature freeze, but
> > drm-misc-next-fixes hasn't been rolled forward yet. I think you need to
> > wait for drm-misc maintainers to do that (I pinged them already), and then
> > put this one there.
>
> I saw that -fixes was updated including Dave's i915 backported revert,
> so I have applied this to drm-misc-next-fixes.
>
> How/when will this show up in drm-misc-next? My drm_fb_helper
> refactoring needs to be rebased on this.

Ask drm-misc maintainers that they need to send out a pull request and
then backmerge drm-next into drm-misc-next for you. Adding them.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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