From e94bd1736f1f60e916a85a80c0b0ebeaae36cce5 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Michel=20D=C3=A4nzer?= Date: Wed, 30 Nov 2016 17:30:01 +0900 Subject: [PATCH] drm: Don't call drm_for_each_crtc with a non-KMS driver MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 --- drivers/gpu/drm/drm_ioctl.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) 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: -- 2.20.1