[PATCH v2 2/2] drm/vc4: hdmi: Fix pointer dereference before check

From: José Expósito
Date: Thu Nov 10 2022 - 08:48:10 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 | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index a49f88e5d2b9..6b223a5fcf6f 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -318,8 +318,8 @@ 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_device *drm;
+ struct vc4_hdmi *vc4_hdmi;
struct drm_connector_state *conn_state;
struct drm_crtc_state *crtc_state;
struct drm_crtc *crtc;
@@ -330,6 +330,7 @@ static int vc4_hdmi_reset_link(struct drm_connector *connector,
if (!connector)
return 0;

+ drm = connector->dev;
ret = drm_modeset_lock(&drm->mode_config.connection_mutex, ctx);
if (ret)
return ret;
@@ -347,6 +348,7 @@ static int vc4_hdmi_reset_link(struct drm_connector *connector,
if (!crtc_state->active)
return 0;

+ vc4_hdmi = connector_to_vc4_hdmi(connector);
if (!vc4_hdmi_supports_scrambling(vc4_hdmi))
return 0;

--
2.25.1