drm: rcar-du: Fix crash when no CMM is available

Commit 3bce3fdd1ff2 ("drm: rcar-du: Don't leak device_link to CMM")
refactored CMM handling, and introduced an incorrect test for CMM
availability. When no CMM is present, the rcrtc->cmm field is NULL,
testing rcrtc->cmm->dev causes a NULL pointer dereference. This slipped
through testing as all tests were run with the CMM present.

Fix this issue by correctly testing for rcrtc->cmm.

Fixes: 3bce3fdd1ff2 ("drm: rcar-du: Don't leak device_link to CMM")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/dri-devel/CAMuHMdXomz9GFDqkBjGX9Sda_GLccPcrihvFbOz0GAitDVNTbw@mail.gmail.com
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260408124205.1962448-1-laurent.pinchart+renesas@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
(cherry picked from commit 3e9a1da270ddff449b1ad9eadc958f43bc204bd2)
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
index 7c36c30a75b63ece95ff8d24652f040cb359ebd1..1a246ebbfc613b8cd86381c625e7490231544adf 100644 (file)
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c
@@ -513,7 +513,7 @@ static void rcar_du_cmm_setup(struct drm_crtc *crtc)
        struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
        struct rcar_cmm_config cmm_config = {};
 
-       if (!rcrtc->cmm->dev)
+       if (!rcrtc->cmm)
                return;
 
        if (drm_lut)
@@ -667,7 +667,7 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc)
        if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
                rcar_du_vsp_disable(rcrtc);
 
-       if (rcrtc->cmm->dev)
+       if (rcrtc->cmm)
                rcar_cmm_disable(rcrtc->cmm->dev);
 
        /*
@@ -726,7 +726,7 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
        struct rcar_du_crtc_state *rstate = to_rcar_crtc_state(crtc->state);
        struct rcar_du_device *rcdu = rcrtc->dev;
 
-       if (rcrtc->cmm->dev)
+       if (rcrtc->cmm)
                rcar_cmm_enable(rcrtc->cmm->dev);
        rcar_du_crtc_get(rcrtc);