inno_hdmi_irq() passes hdmi->bridge.dev to drm_helper_hpd_irq_event(),
which dereferences it in its first statement:
if (!dev->mode_config.poll_enabled)
bridge.dev is assigned only by drm_bridge_attach(), but inno_hdmi_bind()
unmutes the hotplug interrupt in inno_hdmi_init_hw() and installs the
handler well before it attaches the bridge:
inno_hdmi_init_hw(hdmi); /* unmutes hotplug */
devm_request_threaded_irq(...); /* handler goes live */
...
hdmi->bridge.ddc = inno_hdmi_i2c_adapter(hdmi);
devm_drm_bridge_add(dev, &hdmi->bridge);
drm_bridge_attach(...); /* bridge.dev set here */
The bridge is allocated by devm_drm_bridge_alloc(), which kzalloc()s it,
so bridge.dev is NULL for all of that window, and a hotplug event
arriving in it enters drm_helper_hpd_irq_event(NULL).
Before the conversion to a bridge the ordering was safe:
inno_hdmi_register() called drmm_connector_hdmi_init(), which set
connector.dev, before the interrupt was requested.
Drop hotplug events that arrive before the bridge is attached.
Fixes: 969325a2597e ("drm/rockchip: inno-hdmi: Convert to drm bridge")
Signed-off-by: Michal Wilczynski <[email protected]>
---
drivers/gpu/drm/bridge/inno-hdmi.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c
b/drivers/gpu/drm/bridge/inno-hdmi.c
index
d7c33b92e2ddf4ced84d17304463f44be52270b8..d29832249b942dec84fb9d07a0b21ee751fc0486
100644
--- a/drivers/gpu/drm/bridge/inno-hdmi.c
+++ b/drivers/gpu/drm/bridge/inno-hdmi.c
@@ -929,7 +929,13 @@ static irqreturn_t inno_hdmi_irq(int irq, void *dev_id)
{
struct inno_hdmi *hdmi = dev_id;
- drm_helper_hpd_irq_event(hdmi->bridge.dev);
+ /*
+ * The interrupt is requested before the bridge is attached, and
+ * bridge.dev is only set by drm_bridge_attach(). Drop hotplug events
+ * that arrive before then rather than dereference a NULL drm_device.
+ */
+ if (hdmi->bridge.dev)
+ drm_helper_hpd_irq_event(hdmi->bridge.dev);
return IRQ_HANDLED;
}
--
2.34.1
