Add tests for destination rectangle integer overflow before calling the driver's check function. This will ensure that the transitional plane helpers match the behavior of the full atomic helpers by always returning -ERANGE for planes positioned beyond INT_MAX.
Note that the legacy SetPlane ioctl itself also includes similar tests for integer overflow, so the only case where this check really matters is when legacy cursor operations get routed through the universal plane interface internally.
This issue was first noticed with i915 commit:
commit ff42e093e9c9c17a6e1d6aab24875a36795f926e Author: Daniel Vetter daniel.vetter@ffwll.ch Date: Mon Mar 2 16:35:20 2015 +0100
Revert "drm/i915: Switch planes from transitional helpers to full atomic helpers"
The above revert switched us from full atomic helpers back to the transitional helpers, and in doing so we lost the overflow checking here for universal cursor updates. Even though such extreme cursor positions are unlikely to actually happen in the wild, we still don't want there to be a change of behavior when drivers switch from transitional helpers to full helpers.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84269 Signed-off-by: Matt Roper matthew.d.roper@intel.com --- drivers/gpu/drm/drm_plane_helper.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c index 33807e0..1e9e105 100644 --- a/drivers/gpu/drm/drm_plane_helper.c +++ b/drivers/gpu/drm/drm_plane_helper.c @@ -417,6 +417,20 @@ int drm_plane_helper_commit(struct drm_plane *plane, for (i = 0; i < 2; i++) crtc_funcs[i] = crtc[i] ? crtc[i]->helper_private : NULL;
+ /* + * Give drivers some help against integer overflows (and match the + * behavior of the full atomic helpers). + */ + if (plane_state->crtc_w > INT_MAX || + plane_state->crtc_x > INT_MAX - (int32_t) plane_state->crtc_w || + plane_state->crtc_h > INT_MAX || + plane_state->crtc_y > INT_MAX - (int32_t) plane_state->crtc_h) { + DRM_DEBUG_ATOMIC("Invalid CRTC coordinates %ux%u+%d+%d\n", + plane_state->crtc_w, plane_state->crtc_h, + plane_state->crtc_x, plane_state->crtc_y); + return -ERANGE; + } + if (plane_funcs->atomic_check) { ret = plane_funcs->atomic_check(plane, plane_state); if (ret)