[PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Clear the old_state and new_state pointers for every object in
drm_atomic_state_default_clear(). Otherwise
drm_atomic_get_{new,old}_*_state() will hand out stale pointers to
anyone who hasn't first confirmed that the object is in fact part of
the current atomic transcation, if they are called after we've done
the ww backoff dance while hanging on to the same drm_atomic_state.

For example, handle_conflicting_encoders() looks like it could hit
this since it iterates the full connector list and just calls
drm_atomic_get_new_connector_state() for each.

And I believe we have now witnessed this happening at least once in
i915 check_digital_port_conflicts(). Commit 8b69449d2663 ("drm/i915:
Remove last references to drm_atomic_get_existing* macros") changed
the safe drm_atomic_get_existing_connector_state() to the unsafe
drm_atomic_get_new_connector_state(), which opened the doors for
this particular bug there as well.

Cc: stable@vger.kernel.org
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Abhay Kumar <abhay.kumar@intel.com>
Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/drm_atomic.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 7d25c42f22db..c825c76edc1d 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -155,6 +155,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 						       state->connectors[i].state);
 		state->connectors[i].ptr = NULL;
 		state->connectors[i].state = NULL;
+		state->connectors[i].old_state = NULL;
+		state->connectors[i].new_state = NULL;
 		drm_connector_put(connector);
 	}
 
@@ -169,6 +171,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 
 		state->crtcs[i].ptr = NULL;
 		state->crtcs[i].state = NULL;
+		state->crtcs[i].old_state = NULL;
+		state->crtcs[i].new_state = NULL;
 	}
 
 	for (i = 0; i < config->num_total_plane; i++) {
@@ -181,6 +185,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 						   state->planes[i].state);
 		state->planes[i].ptr = NULL;
 		state->planes[i].state = NULL;
+		state->planes[i].old_state = NULL;
+		state->planes[i].new_state = NULL;
 	}
 
 	for (i = 0; i < state->num_private_objs; i++) {
@@ -190,6 +196,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 						 state->private_objs[i].state);
 		state->private_objs[i].ptr = NULL;
 		state->private_objs[i].state = NULL;
+		state->private_objs[i].old_state = NULL;
+		state->private_objs[i].new_state = NULL;
 	}
 	state->num_private_objs = 0;
 
-- 
2.16.1

Re: [PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[Daniel Vetter]

On Wed, May 02, 2018 at 09:32:47PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Clear the old_state and new_state pointers for every object in
> drm_atomic_state_default_clear(). Otherwise
> drm_atomic_get_{new,old}_*_state() will hand out stale pointers to
> anyone who hasn't first confirmed that the object is in fact part of
> the current atomic transcation, if they are called after we've done
> the ww backoff dance while hanging on to the same drm_atomic_state.
> 
> For example, handle_conflicting_encoders() looks like it could hit
> this since it iterates the full connector list and just calls
> drm_atomic_get_new_connector_state() for each.
> 
> And I believe we have now witnessed this happening at least once in
> i915 check_digital_port_conflicts(). Commit 8b69449d2663 ("drm/i915:
> Remove last references to drm_atomic_get_existing* macros") changed
> the safe drm_atomic_get_existing_connector_state() to the unsafe
> drm_atomic_get_new_connector_state(), which opened the doors for
> this particular bug there as well.
> 
> Cc: stable@vger.kernel.org
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Abhay Kumar <abhay.kumar@intel.com>
> Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.")
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Uh ... that's some bad oversight :-/

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

btw for stable we might want to split this into 1 patch for core objects
and 1 patch for driver private stuff. Feel free to do so while applying
and keep my r-b. The fixes line for the 2nd patch would be:

Fixes: a4370c777406 ("drm/atomic: Make private objs proper objects")
Cc: <stable@vger.kernel.org> # v4.14+

Cheers, Daniel
> ---
>  drivers/gpu/drm/drm_atomic.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 7d25c42f22db..c825c76edc1d 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -155,6 +155,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
>  						       state->connectors[i].state);
>  		state->connectors[i].ptr = NULL;
>  		state->connectors[i].state = NULL;
> +		state->connectors[i].old_state = NULL;
> +		state->connectors[i].new_state = NULL;
>  		drm_connector_put(connector);
>  	}
>  
> @@ -169,6 +171,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
>  
>  		state->crtcs[i].ptr = NULL;
>  		state->crtcs[i].state = NULL;
> +		state->crtcs[i].old_state = NULL;
> +		state->crtcs[i].new_state = NULL;
>  	}
>  
>  	for (i = 0; i < config->num_total_plane; i++) {
> @@ -181,6 +185,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
>  						   state->planes[i].state);
>  		state->planes[i].ptr = NULL;
>  		state->planes[i].state = NULL;
> +		state->planes[i].old_state = NULL;
> +		state->planes[i].new_state = NULL;
>  	}
>  
>  	for (i = 0; i < state->num_private_objs; i++) {
> @@ -190,6 +196,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
>  						 state->private_objs[i].state);
>  		state->private_objs[i].ptr = NULL;
>  		state->private_objs[i].state = NULL;
> +		state->private_objs[i].old_state = NULL;
> +		state->private_objs[i].new_state = NULL;
>  	}
>  	state->num_private_objs = 0;
>  
> -- 
> 2.16.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[Maarten Lankhorst]

Op 02-05-18 om 20:32 schreef Ville Syrjala:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Clear the old_state and new_state pointers for every object in
> drm_atomic_state_default_clear(). Otherwise
> drm_atomic_get_{new,old}_*_state() will hand out stale pointers to
> anyone who hasn't first confirmed that the object is in fact part of
> the current atomic transcation, if they are called after we've done
> the ww backoff dance while hanging on to the same drm_atomic_state.
>
> For example, handle_conflicting_encoders() looks like it could hit
> this since it iterates the full connector list and just calls
> drm_atomic_get_new_connector_state() for each.
>
> And I believe we have now witnessed this happening at least once in
> i915 check_digital_port_conflicts(). Commit 8b69449d2663 ("drm/i915:
> Remove last references to drm_atomic_get_existing* macros") changed
> the safe drm_atomic_get_existing_connector_state() to the unsafe
> drm_atomic_get_new_connector_state(), which opened the doors for
> this particular bug there as well.
>
> Cc: stable@vger.kernel.org
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Abhay Kumar <abhay.kumar@intel.com>
> Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.")
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
OUCH! Good catch..

~Maarten

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

How come KASAN didn't complain?

Re: [PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[Ville Syrjälä]

On Thu, May 03, 2018 at 08:35:30AM +0200, Daniel Vetter wrote:
> On Wed, May 02, 2018 at 09:32:47PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Clear the old_state and new_state pointers for every object in
> > drm_atomic_state_default_clear(). Otherwise
> > drm_atomic_get_{new,old}_*_state() will hand out stale pointers to
> > anyone who hasn't first confirmed that the object is in fact part of
> > the current atomic transcation, if they are called after we've done
> > the ww backoff dance while hanging on to the same drm_atomic_state.
> > 
> > For example, handle_conflicting_encoders() looks like it could hit
> > this since it iterates the full connector list and just calls
> > drm_atomic_get_new_connector_state() for each.
> > 
> > And I believe we have now witnessed this happening at least once in
> > i915 check_digital_port_conflicts(). Commit 8b69449d2663 ("drm/i915:
> > Remove last references to drm_atomic_get_existing* macros") changed
> > the safe drm_atomic_get_existing_connector_state() to the unsafe
> > drm_atomic_get_new_connector_state(), which opened the doors for
> > this particular bug there as well.
> > 
> > Cc: stable@vger.kernel.org
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > Cc: Abhay Kumar <abhay.kumar@intel.com>
> > Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.")
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Uh ... that's some bad oversight :-/
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> btw for stable we might want to split this into 1 patch for core objects
> and 1 patch for driver private stuff.

Good point. I forgot we did that after the new iterators were
introduced. I'll do the split.

> Feel free to do so while applying
> and keep my r-b. The fixes line for the 2nd patch would be:
> 
> Fixes: a4370c777406 ("drm/atomic: Make private objs proper objects")
> Cc: <stable@vger.kernel.org> # v4.14+

Ta.

> 
> Cheers, Daniel
> > ---
> >  drivers/gpu/drm/drm_atomic.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 7d25c42f22db..c825c76edc1d 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -155,6 +155,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> >  						       state->connectors[i].state);
> >  		state->connectors[i].ptr = NULL;
> >  		state->connectors[i].state = NULL;
> > +		state->connectors[i].old_state = NULL;
> > +		state->connectors[i].new_state = NULL;
> >  		drm_connector_put(connector);
> >  	}
> >  
> > @@ -169,6 +171,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> >  
> >  		state->crtcs[i].ptr = NULL;
> >  		state->crtcs[i].state = NULL;
> > +		state->crtcs[i].old_state = NULL;
> > +		state->crtcs[i].new_state = NULL;
> >  	}
> >  
> >  	for (i = 0; i < config->num_total_plane; i++) {
> > @@ -181,6 +185,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> >  						   state->planes[i].state);
> >  		state->planes[i].ptr = NULL;
> >  		state->planes[i].state = NULL;
> > +		state->planes[i].old_state = NULL;
> > +		state->planes[i].new_state = NULL;
> >  	}
> >  
> >  	for (i = 0; i < state->num_private_objs; i++) {
> > @@ -190,6 +196,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> >  						 state->private_objs[i].state);
> >  		state->private_objs[i].ptr = NULL;
> >  		state->private_objs[i].state = NULL;
> > +		state->private_objs[i].old_state = NULL;
> > +		state->private_objs[i].new_state = NULL;
> >  	}
> >  	state->num_private_objs = 0;
> >  
> > -- 
> > 2.16.1
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [Intel-gfx] [PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear()

[Ville Syrjälä]

On Thu, May 03, 2018 at 01:41:52PM +0300, Ville Syrjälä wrote:
> On Thu, May 03, 2018 at 08:35:30AM +0200, Daniel Vetter wrote:
> > On Wed, May 02, 2018 at 09:32:47PM +0300, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > Clear the old_state and new_state pointers for every object in
> > > drm_atomic_state_default_clear(). Otherwise
> > > drm_atomic_get_{new,old}_*_state() will hand out stale pointers to
> > > anyone who hasn't first confirmed that the object is in fact part of
> > > the current atomic transcation, if they are called after we've done
> > > the ww backoff dance while hanging on to the same drm_atomic_state.
> > > 
> > > For example, handle_conflicting_encoders() looks like it could hit
> > > this since it iterates the full connector list and just calls
> > > drm_atomic_get_new_connector_state() for each.
> > > 
> > > And I believe we have now witnessed this happening at least once in
> > > i915 check_digital_port_conflicts(). Commit 8b69449d2663 ("drm/i915:
> > > Remove last references to drm_atomic_get_existing* macros") changed
> > > the safe drm_atomic_get_existing_connector_state() to the unsafe
> > > drm_atomic_get_new_connector_state(), which opened the doors for
> > > this particular bug there as well.
> > > 
> > > Cc: stable@vger.kernel.org
> > > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > Cc: Abhay Kumar <abhay.kumar@intel.com>
> > > Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.")
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Uh ... that's some bad oversight :-/
> > 
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > 
> > btw for stable we might want to split this into 1 patch for core objects
> > and 1 patch for driver private stuff.
> 
> Good point. I forgot we did that after the new iterators were
> introduced. I'll do the split.

Pushed the split version for drm-misc-fixes.

As mentioned on irc we don't have any get_{new,old}_private_state()
functions, so the private objs part is pretty theoretical. However
splitting does have the benefit of (hopefully) not requiring manual
intervention when someone tries to cherry-pick this to 4.12/4.13.

Thanks for the reviews.

> 
> > Feel free to do so while applying
> > and keep my r-b. The fixes line for the 2nd patch would be:
> > 
> > Fixes: a4370c777406 ("drm/atomic: Make private objs proper objects")
> > Cc: <stable@vger.kernel.org> # v4.14+
> 
> Ta.
> 
> > 
> > Cheers, Daniel
> > > ---
> > >  drivers/gpu/drm/drm_atomic.c | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > > index 7d25c42f22db..c825c76edc1d 100644
> > > --- a/drivers/gpu/drm/drm_atomic.c
> > > +++ b/drivers/gpu/drm/drm_atomic.c
> > > @@ -155,6 +155,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> > >  						       state->connectors[i].state);
> > >  		state->connectors[i].ptr = NULL;
> > >  		state->connectors[i].state = NULL;
> > > +		state->connectors[i].old_state = NULL;
> > > +		state->connectors[i].new_state = NULL;
> > >  		drm_connector_put(connector);
> > >  	}
> > >  
> > > @@ -169,6 +171,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> > >  
> > >  		state->crtcs[i].ptr = NULL;
> > >  		state->crtcs[i].state = NULL;
> > > +		state->crtcs[i].old_state = NULL;
> > > +		state->crtcs[i].new_state = NULL;
> > >  	}
> > >  
> > >  	for (i = 0; i < config->num_total_plane; i++) {
> > > @@ -181,6 +185,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> > >  						   state->planes[i].state);
> > >  		state->planes[i].ptr = NULL;
> > >  		state->planes[i].state = NULL;
> > > +		state->planes[i].old_state = NULL;
> > > +		state->planes[i].new_state = NULL;
> > >  	}
> > >  
> > >  	for (i = 0; i < state->num_private_objs; i++) {
> > > @@ -190,6 +196,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> > >  						 state->private_objs[i].state);
> > >  		state->private_objs[i].ptr = NULL;
> > >  		state->private_objs[i].state = NULL;
> > > +		state->private_objs[i].old_state = NULL;
> > > +		state->private_objs[i].new_state = NULL;
> > >  	}
> > >  	state->num_private_objs = 0;
> > >  
> > > -- 
> > > 2.16.1
> > > 
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > 
> > -- 
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> 
> -- 
> Ville Syrjälä
> Intel
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel