drm: add a check for x/y in drm_mode_setcrtc

commit 01447e9f04ba1c49a9534ae6a5a6f26c2bb05226 upstream.

legacy setcrtc ioctl does take a 32 bit value which might indeed
overflow

the checks of crtc_req->x > INT_MAX and crtc_req->y > INT_MAX aren't
needed any more with this

v2: -polish the annotation according to Daniel's comment

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Zhao Junwang <zhjwpku@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 0e716fd..20110b4 100644 (file)
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1505,8 +1505,11 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                return -EINVAL;
 
-       /* For some reason crtc x/y offsets are signed internally. */
-       if (crtc_req->x > INT_MAX || crtc_req->y > INT_MAX)
+       /*
+        * Universal plane src offsets are only 16.16, prevent havoc for
+        * drivers using universal plane code internally.
+        */
+       if (crtc_req->x & 0xffff0000 || crtc_req->y & 0xffff0000)
                return -ERANGE;
 
        mutex_lock(&dev->mode_config.mutex);