linux-kernel - [PATCH 5.10 201/545] drm/vc4: hdmi: Dont access the connector state in reset if kmalloc fails

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Message-Id: <20220819153838.387286468@linuxfoundation.org>
Date:   Fri, 19 Aug 2022 17:39:31 +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, Thomas Zimmermann <tzimmermann@...e.de>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Maxime Ripard <maxime@...no.tech>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 201/545] drm/vc4: hdmi: Dont access the connector state in reset if kmalloc fails

From: Maxime Ripard <maxime@...no.tech>

[ Upstream commit e55a07751146ef8ebc2c561564437b78f46405d3 ]

drm_atomic_helper_connector_reset uses kmalloc which, from an API
standpoint, can fail, and thus setting connector->state to NULL.
However, our reset hook then calls drm_atomic_helper_connector_tv_reset
that will access connector->state without checking if it's a valid
pointer or not.

Make sure we don't end up accessing a NULL pointer.

Acked-by: Thomas Zimmermann <tzimmermann@...e.de>
Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Suggested-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215154243.540115-5-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 9a90f22df3d2..978afe706ee2 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -209,7 +209,9 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 static void vc4_hdmi_connector_reset(struct drm_connector *connector)
 {
 	drm_atomic_helper_connector_reset(connector);
-	drm_atomic_helper_connector_tv_reset(connector);
+
+	if (connector->state)
+		drm_atomic_helper_connector_tv_reset(connector);
 }
 
 static const struct drm_connector_funcs vc4_hdmi_connector_funcs = {
-- 
2.35.1