From: Charles Keepax Date: Tue, 17 Feb 2015 17:14:41 +0000 (+0000) Subject: drm/exynos: Check for NULL dereference of crtc X-Git-Tag: firefly_0821_release~176^2~2122^2~3^2~2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=995fdfb9c8e9cf9707966c6936eb6ea1a8b68194;p=firefly-linux-kernel-4.4.55.git drm/exynos: Check for NULL dereference of crtc The commit "drm/exynos: remove exynos_plane_dpms" (d9ea6256) removed the use of the enabled flag, which means that the code may attempt to call win_enable on a NULL crtc. This results in the following oops on Arndale: [ 1.673479] Unable to handle kernel NULL pointer dereference at virtual address 00000368 [ 1.681500] pgd = c0004000 [ 1.684154] [00000368] *pgd=00000000 [ 1.687713] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 1.693012] Modules linked in: [ 1.696045] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.19.0-07545-g57485fa #1907 [ 1.703524] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) (....) [ 2.014803] [] (exynos_plane_destroy) from [] (drm_mode_config_cleanup+0x168/0x20c) [ 2.024178] [] (drm_mode_config_cleanup) from [] (exynos_drm_load+0xac/0x12c) This patch adds in a check to ensure exynos_crtc is not NULL before it is dereferenced. Signed-off-by: Charles Keepax Signed-off-by: Inki Dae --- diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c index a5616872eee7..8ad5b7294eb4 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_plane.c +++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c @@ -175,7 +175,7 @@ static int exynos_disable_plane(struct drm_plane *plane) struct exynos_drm_plane *exynos_plane = to_exynos_plane(plane); struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(plane->crtc); - if (exynos_crtc->ops->win_disable) + if (exynos_crtc && exynos_crtc->ops->win_disable) exynos_crtc->ops->win_disable(exynos_crtc, exynos_plane->zpos);