[PATCH] drm/vc4: hdmi: Fix pointer dereference before check

From: José Expósito
Date: Sat Oct 29 2022 - 05:34:54 EST


Commit 6bed2ea3cb38 ("drm/vc4: hdmi: Reset link on hotplug") introduced
the vc4_hdmi_reset_link() function. This function dereferences the
"connector" pointer before checking whether it is NULL or not.

Rework variable assignment to avoid this issue.

Fixes: 6bed2ea3cb38 ("drm/vc4: hdmi: Reset link on hotplug")
Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 4a73fafca51b..07d058b6afb7 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -319,9 +319,9 @@ static int reset_pipe(struct drm_crtc *crtc,
static int vc4_hdmi_reset_link(struct drm_connector *connector,
struct drm_modeset_acquire_ctx *ctx)
{
- struct drm_device *drm = connector->dev;
- struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
- struct drm_encoder *encoder = &vc4_hdmi->encoder.base;
+ struct drm_device *drm;
+ struct vc4_hdmi *vc4_hdmi;
+ struct drm_encoder *encoder;
struct drm_connector_state *conn_state;
struct drm_crtc_state *crtc_state;
struct drm_crtc *crtc;
@@ -332,6 +332,10 @@ static int vc4_hdmi_reset_link(struct drm_connector *connector,
if (!connector)
return 0;

+ drm = connector->dev;
+ vc4_hdmi = connector_to_vc4_hdmi(connector);
+ encoder = &vc4_hdmi->encoder.base;
+
ret = drm_modeset_lock(&drm->mode_config.connection_mutex, ctx);
if (ret)
return ret;
--
2.25.1