Messages in this thread | | | Subject | Re: [PATCH v1] drm/simple_kms_helper: Fix NULL pointer dereference with no active CRTC | From | Oleksandr Andrushchenko <> | Date | Thu, 22 Feb 2018 08:12:48 +0200 |
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On 02/22/2018 08:09 AM, 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> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > --- > Changes since initial: > - re-worked checks for null CRTC as suggested by Daniel Vetter > --- > drivers/gpu/drm/drm_simple_kms_helper.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c > index 9ca8a4a59b74..4a1dbd88b1ec 100644 > --- a/drivers/gpu/drm/drm_simple_kms_helper.c > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c > @@ -121,12 +121,6 @@ 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->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, > @@ -137,7 +131,9 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, > return ret; > > if (!plane_state->visible) > - return -EINVAL; Daniel, I have put your R-b tag, but I had removed suggested "WARN_ON(crtc_state && crtc_state->enable);" here as it fires each time when crtc_state is not NULL. Please let me know if this is not ok and you want me to remove your R-b tag. > + return 0; > + > + drm_mode_get_hv_timing(&crtc_state->mode, &clip.x2, &clip.y2); > > if (!pipe->funcs || !pipe->funcs->check) > return 0; Thank you, Oleksandr
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