| Message ID | d676eef9-55b2-a7fd-be9b-4d53d59610a9@epam.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Feb 19, 2018 at 04:58:43PM +0200, Oleksandr Andrushchenko wrote: > On 02/19/2018 04:30 PM, Daniel Vetter wrote: > > On Tue, Feb 13, 2018 at 10:44:16AM +0200, Oleksandr Andrushchenko wrote: > > > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> > > > > > > It is possible that drm_simple_kms_plane_atomic_check called > > > with no CRTC set, e.g. when user-space application sets CRTC_ID/FB_ID > > > to 0 before doing any actual drawing. This leads to NULL pointer > > > dereference because in this case new CRTC state is NULL and must be > > > checked before accessing. > > > > > > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> > > > --- > > > drivers/gpu/drm/drm_simple_kms_helper.c | 6 ++++-- > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c > > > index 9ca8a4a59b74..a05eca9cec8b 100644 > > > --- a/drivers/gpu/drm/drm_simple_kms_helper.c > > > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c > > > @@ -121,8 +121,10 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, > > > pipe = container_of(plane, struct drm_simple_display_pipe, plane); > > > crtc_state = drm_atomic_get_new_crtc_state(plane_state->state, > > > &pipe->crtc); > > > - if (!crtc_state->enable) > > > - return 0; /* nothing to check when disabling or disabled */ > > > + > > > + if (!crtc_state || !crtc_state->enable) > > > + /* nothing to check when disabling or disabled or no CRTC set */ > > > + return 0; > > > if (crtc_state->enable) > > > drm_mode_get_hv_timing(&crtc_state->mode, > > Hm, this is a bit annoying, since the can_position = false parameter to > > drm_atomic_helper_check_plane_state is supposed to catch all this. Would > > moving all the checks after the call to that helper, and gating them on > > plane_state->visible also work? > Yes, it does work if this is what you mean: I wasn't sure, thanks for figuring this out! > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c > b/drivers/gpu/drm/drm_simple_kms_helper.c > index a05eca9cec8b..c48858bb2823 100644 > --- a/drivers/gpu/drm/drm_simple_kms_helper.c > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c > @@ -122,14 +122,6 @@ static int drm_simple_kms_plane_atomic_check(struct > drm_plane *plane, > crtc_state = drm_atomic_get_new_crtc_state(plane_state->state, > &pipe->crtc); > > - if (!crtc_state || !crtc_state->enable) > - /* nothing to check when disabling or disabled or no CRTC > set */ > - return 0; > - > - if (crtc_state->enable) > - drm_mode_get_hv_timing(&crtc_state->mode, > - &clip.x2, &clip.y2); > - > ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state, > &clip, > DRM_PLANE_HELPER_NO_SCALING, > @@ -138,6 +130,13 @@ static int drm_simple_kms_plane_atomic_check(struct > drm_plane *plane, > if (ret) > return ret; > > + if (!plane_state->visible || !crtc_state->enable) > + return 0; /* nothing to check when disabling or disabled */ if (!plane_state->visible) { WARN_ON(crtc_state->enabled); return 0; } The helper call above should guarantee this. > + > + if (plane_state->visible && crtc_state->enable) Similar here. > + drm_mode_get_hv_timing(&crtc_state->mode, > + &clip.x2, &clip.y2); > + > if (!plane_state->visible) > return -EINVAL; This can now be removed, the plane helper takes care of checking for plane_state->visible != crtc_state->enable. Please also remove. > > We'd need to add a guarantee to drm_atomic_helper_check_plane_state that > > it can cope with crtc_state == NULL, but I think that's a good idea > > anyway. Atm it shouldn't end up looking at the crtc_state pointer in that > > case. > It doesn't look at it at the moment > > Otherwise we'll just go with your fix, but it feels all a bit too fragile, > > hence why I want to explore more robust options a bit. > At list with the change above it passes my test which failed > before. Although I cannot confirm it works for others, but it > certainly does for me. > > -Daniel > Do you want me to send v1 with the code above? Yes please, with my above cleanup suggestions. Thanks, Daniel
diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c index a05eca9cec8b..c48858bb2823 100644 --- a/drivers/gpu/drm/drm_simple_kms_helper.c +++ b/drivers/gpu/drm/drm_simple_kms_helper.c @@ -122,14 +122,6 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, crtc_state = drm_atomic_get_new_crtc_state(plane_state->state, &pipe->crtc); - if (!crtc_state || !crtc_state->enable) - /* nothing to check when disabling or disabled or no CRTC set */ - return 0; - - if (crtc_state->enable) - drm_mode_get_hv_timing(&crtc_state->mode, - &clip.x2, &clip.y2); - ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,