From:   Jiasheng Jiang <jiasheng@iscas.ac.cn>
To:     liviu.dudau@arm.com, brian.starkey@arm.com, airlied@linux.ie,
        daniel@ffwll.ch
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Jiasheng Jiang <jiasheng@iscas.ac.cn>
Subject: [PATCH] drm/arm/mali: Check for NULL pointer after calling kzalloc
Date:   Fri, 14 Jan 2022 17:44:38 +0800
Message-Id: <20220114094438.1319522-1-jiasheng@iscas.ac.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

As the possible failure of the kzalloc(), mw_state could be NULL
pointer.
Therefore, it should be better to check it in order to avoid the
dereference of the NULL pointer, like the kzalloc() in
malidp_mw_connector_duplicate_state().
If fails, we can directly use the 'NULL' instead of the
'&mw_state->base' and __drm_atomic_helper_connector_reset() will deal
with it correctly.

Fixes: 8cbc5caf36ef ("drm: mali-dp: Add writeback connector")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
 drivers/gpu/drm/arm/malidp_mw.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
index f5847a79dd7e..96752353b5a1 100644
--- a/drivers/gpu/drm/arm/malidp_mw.c
+++ b/drivers/gpu/drm/arm/malidp_mw.c
@@ -70,7 +70,11 @@ static void malidp_mw_connector_reset(struct drm_connector *connector)
 		__drm_atomic_helper_connector_destroy_state(connector->state);
 
 	kfree(connector->state);
-	__drm_atomic_helper_connector_reset(connector, &mw_state->base);
+
+	if (!mw_state)
+		__drm_atomic_helper_connector_reset(connector, NULL);
+	else
+		__drm_atomic_helper_connector_reset(connector, &mw_state->base);
 }
 
 static enum drm_connector_status
-- 
2.25.1