linux-kernel - [PATCH v2 2/6] gpu/drm: ingenic: Avoid null pointer deference in plane atomic update

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Message-Id: <20191210144142.33143-2-paul@crapouillou.net>
Date:   Tue, 10 Dec 2019 15:41:38 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH v2 2/6] gpu/drm: ingenic: Avoid null pointer deference in plane atomic update

It is possible that there is no drm_framebuffer associated with a given
plane state.

v2: Handle drm_plane->state which can be NULL too

Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---
 drivers/gpu/drm/ingenic/ingenic-drm.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm.c b/drivers/gpu/drm/ingenic/ingenic-drm.c
index 2e2ed653e9c6..f156f245fdec 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm.c
@@ -371,14 +371,18 @@ static void ingenic_drm_plane_atomic_update(struct drm_plane *plane,
 	struct ingenic_drm *priv = drm_plane_get_priv(plane);
 	struct drm_plane_state *state = plane->state;
 	unsigned int width, height, cpp;
+	dma_addr_t addr;
 
-	width = state->crtc->state->adjusted_mode.hdisplay;
-	height = state->crtc->state->adjusted_mode.vdisplay;
-	cpp = state->fb->format->cpp[plane->index];
+	if (state && state->fb) {
+		addr = drm_fb_cma_get_gem_addr(state->fb, state, 0);
+		width = state->crtc->state->adjusted_mode.hdisplay;
+		height = state->crtc->state->adjusted_mode.vdisplay;
+		cpp = state->fb->format->cpp[plane->index];
 
-	priv->dma_hwdesc->addr = drm_fb_cma_get_gem_addr(state->fb, state, 0);
-	priv->dma_hwdesc->cmd = width * height * cpp / 4;
-	priv->dma_hwdesc->cmd |= JZ_LCD_CMD_EOF_IRQ;
+		priv->dma_hwdesc->addr = addr;
+		priv->dma_hwdesc->cmd = width * height * cpp / 4;
+		priv->dma_hwdesc->cmd |= JZ_LCD_CMD_EOF_IRQ;
+	}
 }
 
 static void ingenic_drm_encoder_atomic_mode_set(struct drm_encoder *encoder,
-- 
2.24.0