linux-kernel - [PATCH 4.19 44/72] drm/tegra: hub: Fix dereference before check

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Date:   Thu,  2 May 2019 17:21:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Thierry Reding <treding@...dia.com>,
        "Sasha Levin (Microsoft)" <sashal@...nel.org>
Subject: [PATCH 4.19 44/72] drm/tegra: hub: Fix dereference before check

[ Upstream commit 7cf77b273a8fc51e7de622fa6691abd4436a9a6b ]

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Thierry Reding <treding@...dia.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@...nel.org>
---
 drivers/gpu/drm/tegra/hub.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c
index 8f4fcbb515fb..bb97cad1eb69 100644
--- a/drivers/gpu/drm/tegra/hub.c
+++ b/drivers/gpu/drm/tegra/hub.c
@@ -378,14 +378,16 @@ static int tegra_shared_plane_atomic_check(struct drm_plane *plane,
 static void tegra_shared_plane_atomic_disable(struct drm_plane *plane,
 					      struct drm_plane_state *old_state)
 {
-	struct tegra_dc *dc = to_tegra_dc(old_state->crtc);
 	struct tegra_plane *p = to_tegra_plane(plane);
+	struct tegra_dc *dc;
 	u32 value;
 
 	/* rien ne va plus */
 	if (!old_state || !old_state->crtc)
 		return;
 
+	dc = to_tegra_dc(old_state->crtc);
+
 	/*
 	 * XXX Legacy helpers seem to sometimes call ->atomic_disable() even
 	 * on planes that are already disabled. Make sure we fallback to the
-- 
2.19.1