From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 544DFCDE009 for ; Thu, 25 Jun 2026 10:44:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E352A10F245; Thu, 25 Jun 2026 10:44:16 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="S040DzGU"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2610B10E1D7; Thu, 25 Jun 2026 10:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782384254; x=1813920254; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=ox2VHxHbUs26Ni59OI8XgN8aYvGnixGst5y0T/QA9lc=; b=S040DzGUJ9nfKNBWirgrrjKnHzgL5t2XCu29Z0RazjgXgfp33aAcmn6c SIf0A8UZSdP/0N9lb3nXIkCdofVm7a/ZiBzs6TqRvVVx86nQD/9dKsI7q 7Fb3HcwgfX9MRAME8Ofi0BI71OmGkd4M0os1kOU4oRjwIw3uT0DXq/Zko ajJ+byeo7JPwCRWriKFyKp7/kvM55593TJFFj/mgOK1+E0+jVJznpZGuT 0JS7CD9dH1fm8SHUPheV1Q8/S9pb+Jzxr5C4FLC7J/5a9xMGQ1fckVs6Y kZv0meXemamtST/Z66tOrSIvJbdf5YzLwqEUIjPQZMqFpnpeD9OLZWC1w w==; X-CSE-ConnectionGUID: von6Pt90QUKYL0cXZ98ldQ== X-CSE-MsgGUID: kYgbDr6zQ9SG1MAlHs3SXA== X-IronPort-AV: E=McAfee;i="6800,10657,11827"; a="83254767" X-IronPort-AV: E=Sophos;i="6.24,224,1774335600"; d="scan'208";a="83254767" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2026 03:44:14 -0700 X-CSE-ConnectionGUID: qhR+zweIQWOIdCgu//38ww== X-CSE-MsgGUID: 401S0iDuQyCIsMcpD2ulQA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,224,1774335600"; d="scan'208";a="250732423" Received: from ijarvine-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.245.126]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2026 03:44:12 -0700 From: Jani Nikula To: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Cc: jani.nikula@intel.com, Martin Hodo , stable@vger.kernel.org, Suraj Kandpal Subject: [PATCH] drm/i915/hdcp: require monotonically increasing seq_num_v Date: Thu, 25 Jun 2026 13:44:07 +0300 Message-ID: <20260625104407.1025614-1-jani.nikula@intel.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland Content-Transfer-Encoding: 8bit X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The HDCP 2.2 specification requires the seq_num_v to be monotonically increasing, and repeated seq_num_v needs to be treated as an integrity failure. Make it so. For the first message, seq_num_v must be zero, and is already checked. We can only check for less-than-or-equal for the subsequent messages, where hdcp2_encrypted is true. Discovered using AI-assisted static analysis confirmed by Intel Product Security. Reported-by: Martin Hodo Fixes: d849178e2c9e ("drm/i915: Implement HDCP2.2 repeater authentication") Cc: # v5.2+ Cc: Suraj Kandpal Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/display/intel_hdcp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c index e88fec24af49..d097b478d010 100644 --- a/drivers/gpu/drm/i915/display/intel_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c @@ -1798,9 +1798,10 @@ int hdcp2_authenticate_repeater_topology(struct intel_connector *connector) return -EINVAL; } - if (seq_num_v < hdcp->seq_num_v) { - /* Roll over of the seq_num_v from repeater. Reauthenticate. */ - drm_dbg_kms(display->drm, "Seq_num_v roll over.\n"); + if (hdcp->hdcp2_encrypted && seq_num_v <= hdcp->seq_num_v) { + /* Reauthenticate on Seq_num_v repeat or rollover */ + drm_dbg_kms(display->drm, "Seq_num_v %s\n", + seq_num_v == hdcp->seq_num_v ? "repeat" : "rollover"); return -EINVAL; } -- 2.47.3