[PATCH 6.6.y v2 2/2] drm/i915/hdcp: Add encoder check in hdcp2_get_capability

[Artem Dinaburg <artem@trailofbits.com>]

From: Suraj Kandpal <suraj.kandpal@intel.com>

[ Upstream commit d34f4f058edf1235c103ca9c921dc54820d14d40 ]

Add encoder check in intel_hdcp2_get_capability to avoid
null pointer error.

[ Backport to 6.6.y: this tree predates the later intel_connector
  conversion, so the unsafe intel_attached_dig_port() call is still in
  intel_hdcp2_capable() rather than the DP and HDMI shims.
  Put the same encoder guard before that common dereference and return
  false through the bool API when no encoder is attached. ]

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240722064451.3610512-3-suraj.kandpal@intel.com
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
---
CVE: CVE-2024-53050
Upstream: d34f4f058edf1235c103ca9c921dc54820d14d40
Backport: guard the common 6.6.y bool helper because the later DP/HDMI
split is not present in this tree.
Review: https://lore.kernel.org/r/2026-09-29-daily-reply-0012-re-i915-hdcp-encoder-check-v2-6-6@kernel.org

 drivers/gpu/drm/i915/display/intel_hdcp.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
index f7987fb90bb1..89e378f71d67 100644
--- a/drivers/gpu/drm/i915/display/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
@@ -168,11 +168,16 @@ bool intel_hdcp_capable(struct intel_connector *connector)
 /* Is HDCP2.2 capable on Platform and Sink */
 bool intel_hdcp2_capable(struct intel_connector *connector)
 {
-	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
+	struct intel_digital_port *dig_port;
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_hdcp *hdcp = &connector->hdcp;
 	bool capable = false;
 
+	if (!intel_attached_encoder(connector))
+		return capable;
+
+	dig_port = intel_attached_dig_port(connector);
+
 	/* I915 support for HDCP2.2 */
 	if (!hdcp->hdcp2_supported)
 		return false;
-- 
2.39.5