From: Michel Dänzer Date: Wed, 30 Nov 2016 08:30:01 +0000 (+0900) Subject: drm: Don't call drm_for_each_crtc with a non-KMS driver X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e94bd1736f1f60e916a85a80c0b0ebeaae36cce5;p=linux-beck.git drm: Don't call drm_for_each_crtc with a non-KMS driver 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 Fixes: f837297ad824 ("drm: Add DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE/RELATIVE flags v2") Cc: stable@vger.kernel.org Signed-off-by: Michel Dänzer Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161130083002.1520-1-michel@daenzer.net --- diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 0ad2c47f808f..71c3473476c7 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -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: