From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DC263C3F4C; Thu, 30 Jul 2026 15:14:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424496; cv=none; b=AgT9lP1Sa6KJviiVxW7DNCSw+eeqAlKtWUlJEu5lMJeIyFa7gAuy0yI6ZTStDdcMLuBs6q/aa5cAMN6QvAHr3IWlbnlU+4NcengGkrSVNttkHnCQYi95vE0q7Q15cQw+Tababp5Cg+V0V/xHTPKIvB0SOzqx67ftlmgx6hvSul4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424496; c=relaxed/simple; bh=FlHArLU8LFcQfmY4ICv46BHCv7N5DOOqRupEk5KLTv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hsRyijZmy0MXOxQjp+zbhUf0mHvt8QAjRDLbMxZwGpYdswlmtSqFEwhjOvOaeApQ8E3LEGDpII9HUhqFCnuNI6OCvmyqldRN1vHIVVVt+3Ez686Y8y7y61Jk6Qnf7KsEbH2JO8UBhVAdFN5JT803ctJGqQ8LQuOGcmE/88zcXOg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iLaDfmJv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="iLaDfmJv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 495381F000E9; Thu, 30 Jul 2026 15:14:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785424494; bh=PYdm6u6NQ4hH6/6i/VhYdE5VoCy0/XsMEWJzEeTjWKo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iLaDfmJvRLW4tFSYz6holXJ1Fh4Cfk9IUxJNPIpmpWP+eKI/eq2mYa7LU0PJI68zg TByhvNnlgPJRgMaijXGTjlB83A8/gmya/qKCFqc2xk3XsuBnx42hJqedPrJfj2mU87 +xwW7wlebuFkX1dTu3z4VVlw+6LvzI4Ttj92nMwY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin Hodo , Suraj Kandpal , Jani Nikula , Joonas Lahtinen Subject: [PATCH 6.18 359/675] drm/i915/hdcp: require monotonically increasing seq_num_v Date: Thu, 30 Jul 2026 16:11:29 +0200 Message-ID: <20260730141452.761415586@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jani Nikula commit db9e64c983dcb07ff256bd455f258c44aa530ff8 upstream. 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: stable@vger.kernel.org # v5.2+ Cc: Suraj Kandpal Reviewed-by: Suraj Kandpal Link: https://patch.msgid.link/20260625104407.1025614-1-jani.nikula@intel.com Signed-off-by: Jani Nikula (cherry picked from commit 58a224375c81179b52558c53d8857b93196d2687) Signed-off-by: Joonas Lahtinen Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/display/intel_hdcp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/i915/display/intel_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c @@ -1794,9 +1794,10 @@ int hdcp2_authenticate_repeater_topology 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; }