From f0b408eebc993310bea3f2daae286c40bd3f063b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Wed, 2 May 2018 21:32:47 +0300 Subject: [PATCH] drm/atomic: Clean old_state/new_state in drm_atomic_state_default_clear() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. v2: Split private objs out to a separate patch (Daniel) Cc: stable@vger.kernel.org Cc: Maarten Lankhorst Cc: Laurent Pinchart Cc: Abhay Kumar Fixes: 581e49fe6b41 ("drm/atomic: Add new iterators over all state, v3.") Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20180502183247.5746-1-ville.syrjala@linux.intel.com Reviewed-by: Maarten Lankhorst Reviewed-by: Daniel Vetter Signed-off-by: Sean Paul --- drivers/gpu/drm/drm_atomic.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 7d25c42f22db..4fa19ed7517a 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++) { -- 2.20.1