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drm: Don't call drm_for_each_crtc with a non-KMS driver

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Fixes oops if userspace calls DRM_IOCTL_GET_CAP for
 DRM_CAP_PAGE_FLIP_TARGET on a non-KMS device node. (Normal userspace
doesn't do that, discovered by syzkaller)

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Fixes: f837297ad824 ("drm: Add DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE/RELATIVE flags v2")
Cc: stable@vger.kernel.org
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161130083002.1520-1-michel@daenzer.net
This commit is contained in:
Michel Dänzer 2016-11-30 17:30:01 +09:00 committed by Daniel Vetter
parent e5517c2a5a
commit e94bd1736f
1 changed files with 6 additions and 4 deletions
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10
drivers/gpu/drm/drm_ioctl.c
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@ -254,10 +254,12 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
req->value = dev->mode_config.async_page_flip;
break;
case DRM_CAP_PAGE_FLIP_TARGET:
req->value = 1;
drm_for_each_crtc(crtc, dev) {
if (!crtc->funcs->page_flip_target)
req->value = 0;
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
req->value = 1;
drm_for_each_crtc(crtc, dev) {
if (!crtc->funcs->page_flip_target)
req->value = 0;
}
}
break;
case DRM_CAP_CURSOR_WIDTH: