linux-kernel - [PATCH AUTOSEL 6.0 07/30] drm/rockchip: vop2: fix null pointer in plane_atomic

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Date:   Thu, 10 Nov 2022 21:33:15 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Michael Tretter <m.tretter@...gutronix.de>,
        Heiko Stuebner <heiko@...ech.de>,
        Sasha Levin <sashal@...nel.org>, hjc@...k-chips.com,
        airlied@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: [PATCH AUTOSEL 6.0 07/30] drm/rockchip: vop2: fix null pointer in plane_atomic_disable

From: Michael Tretter <m.tretter@...gutronix.de>

[ Upstream commit 471bf2406c043491b1a8288e5f04bc278f7d7ca1 ]

If the vop2_plane_atomic_disable function is called with NULL as a
state, accessing the old_pstate runs into a null pointer exception.
However, the drm_atomic_helper_disable_planes_on_crtc function calls the
atomic_disable callback with state NULL.

Allow to disable a plane without passing a plane state by checking the
old_pstate only if a state is passed.

Signed-off-by: Michael Tretter <m.tretter@...gutronix.de>
Signed-off-by: Heiko Stuebner <heiko@...ech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221028095206.2136601-2-m.tretter@pengutronix.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index f9aa8b96c695..bf9c3e92e1cd 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -997,13 +997,15 @@ static int vop2_plane_atomic_check(struct drm_plane *plane,
 static void vop2_plane_atomic_disable(struct drm_plane *plane,
 				      struct drm_atomic_state *state)
 {
-	struct drm_plane_state *old_pstate = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_plane_state *old_pstate = NULL;
 	struct vop2_win *win = to_vop2_win(plane);
 	struct vop2 *vop2 = win->vop2;
 
 	drm_dbg(vop2->drm, "%s disable\n", win->data->name);
 
-	if (!old_pstate->crtc)
+	if (state)
+		old_pstate = drm_atomic_get_old_plane_state(state, plane);
+	if (old_pstate && !old_pstate->crtc)
 		return;
 
 	vop2_win_disable(win);
-- 
2.35.1