[PATCH 3.4 017/107] drm: add a check for x/y in drm_mode_setcrtc

lizf
2016-03-16T08:08:09Z

From: Zhao Junwang <zhjwpku@gmail.com>

3.4.111-rc1 review patch. If anyone has any objections, please let me know.

------------------

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: Zefan Li <lizefan@huawei.com>
---
drivers/gpu/drm/drm_crtc.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index c61e672..ed4b748 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1836,8 +1836,11 @@ 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);
--
1.9.1