From 0e81807e647c5e12fd897f3d520252ea60de3ff9 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Thu, 15 Nov 2018 11:58:51 +0100 Subject: [PATCH] drm/vc4: Fix NULL pointer dereference in the async update path vc4_plane_atomic_async_update() calls vc4_plane_atomic_check() which in turn calls vc4_plane_setup_clipping_and_scaling(), and since commit 58a6a36fe8e0 ("drm/vc4: Use drm_atomic_helper_check_plane_state() to simplify the logic"), this function accesses plane_state->state which will be NULL when called from the async update path because we're passing the current plane state, and plane_state->state has been assigned to NULL in drm_atomic_helper_swap_state(). Pass the new state instead of the current one (the new state has ->state set to a non-NULL value). Fixes: 58a6a36fe8e0 ("drm/vc4: Use drm_atomic_helper_check_plane_state() to simplify the logic") Signed-off-by: Boris Brezillon Reviewed-by: Eric Anholt Link: https://patchwork.freedesktop.org/patch/msgid/20181115105852.9844-1-boris.brezillon@bootlin.com --- drivers/gpu/drm/vc4/vc4_plane.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/vc4/vc4_plane.c +++ b/drivers/gpu/drm/vc4/vc4_plane.c @@ -905,7 +905,7 @@ void vc4_plane_async_set_fb(struct drm_p static void vc4_plane_atomic_async_update(struct drm_plane *plane, struct drm_plane_state *state) { - struct vc4_plane_state *vc4_state = to_vc4_plane_state(plane->state); + struct vc4_plane_state *vc4_state, *new_vc4_state; if (plane->state->fb != state->fb) { vc4_plane_async_set_fb(plane, state->fb); @@ -927,7 +927,18 @@ static void vc4_plane_atomic_async_updat plane->state->src_y = state->src_y; /* Update the display list based on the new crtc_x/y. */ - vc4_plane_atomic_check(plane, plane->state); + vc4_plane_atomic_check(plane, state); + + new_vc4_state = to_vc4_plane_state(state); + vc4_state = to_vc4_plane_state(plane->state); + + /* Update the current vc4_state pos0, pos2 and ptr0 dlist entries. */ + vc4_state->dlist[vc4_state->pos0_offset] = + new_vc4_state->dlist[vc4_state->pos0_offset]; + vc4_state->dlist[vc4_state->pos2_offset] = + new_vc4_state->dlist[vc4_state->pos2_offset]; + vc4_state->dlist[vc4_state->ptr0_offset] = + new_vc4_state->dlist[vc4_state->ptr0_offset]; /* Note that we can't just call vc4_plane_write_dlist() * because that would smash the context data that the HVS is