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 54B46CD6E51 for ; Fri, 29 May 2026 15:17:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6923F1120BC; Fri, 29 May 2026 15:17:02 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="hAljyH7S"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id CBAC41120B9; Fri, 29 May 2026 15:17:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1780067820; x=1811603820; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=HedptQ/6CIwjp4YiEkdapvOi2Wo7J+jtmUPcqWAfNeo=; b=hAljyH7SS6gcYFpHXFPAgOu8ULYOEJYxK4154M7c/34TycN/kfm35yEj vaw1qI4j1OQ24dVY0IOgYKUQSWgno61LS0HL0I3udo7u7G+32pobJEJuO jai+mrWTLS1RYMXjcwDmgjHZCPGWl5dj/UuXXUSwnemB5w7oCwPhLcuSD IxiVQn8RneG7EUkqlqqUAebF18zbFuOS8bbP673g4K8VLS2INo08wvqB0 d+5RCV/jPdnLtfU8lrsVQUiShnFzohNg/sI1IbEwKpMiQy8+nng11o2Da iCs1dFHz0Wp6rJC2sSyq7sPOSdIBzr4IIpKb79eyuj7qoCUQ7kyIFacSe A==; X-CSE-ConnectionGUID: jL5M7Ch0TOCorgoPQ/s7Pg== X-CSE-MsgGUID: JUoVW7r0RkiYyrhGZVf5VQ== X-IronPort-AV: E=McAfee;i="6800,10657,11801"; a="81035499" X-IronPort-AV: E=Sophos;i="6.24,175,1774335600"; d="scan'208";a="81035499" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 May 2026 08:17:00 -0700 X-CSE-ConnectionGUID: i6bFdGVTS82BuB4IRgzZTA== X-CSE-MsgGUID: CaBophDrRayP69jpuH6lKw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,175,1774335600"; d="scan'208";a="273187289" Received: from kniemiec-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.147]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 May 2026 08:16:57 -0700 From: Jani Nikula To: Nikita Zhandarovich , Rodrigo Vivi , Joonas Lahtinen Cc: Nikita Zhandarovich , Tvrtko Ursulin , David Airlie , Simona Vetter , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org Subject: Re: [PATCH v2] drm/i915/edp: Check supported link rates DPCD read In-Reply-To: <20260529145759.1640646-1-n.zhandarovich@fintech.ru> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland References: <20260529145759.1640646-1-n.zhandarovich@fintech.ru> Date: Fri, 29 May 2026 18:16:54 +0300 Message-ID: <824c6ced1095635f86527709822c8af3ddff7c8c@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 29 May 2026, Nikita Zhandarovich wrote: > intel_edp_set_sink_rates() reads DP_SUPPORTED_LINK_RATES into a local > stack array and then parses the array unconditionally. If the read > fails, the array contents are not valid and may result in bogus sink > link rates being used. > > Use drm_dp_dpcd_read_data() and clear the sink rate array on failure, > so the existing parser falls back to the default sink rate handling. > > Found by Linux Verification Center (linuxtesting.org) with static > analysis tool SVACE. > > Fixes: 68f357cb7347 ("drm/i915/dp: generate and cache sink rate array for all DP, not just eDP 1.4") > Signed-off-by: Nikita Zhandarovich Reviewed-by: Jani Nikula > --- > v1 -> v2: > - Use drm_dp_dpcd_read_data() instead of drm_dp_dpcd_read(). > - Avoid the goto by clearing sink_rates on read failure, as suggested by > Jani Nikula. > - Adjust patch description. > > drivers/gpu/drm/i915/display/intel_dp.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > index 6ef2a0043cda..5c3e816b0135 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -4678,10 +4678,17 @@ intel_edp_set_sink_rates(struct intel_dp *intel_dp) > > if (intel_dp->edp_dpcd[0] >= DP_EDP_14) { > __le16 sink_rates[DP_MAX_SUPPORTED_RATES]; > + int ret; > int i; > > - drm_dp_dpcd_read(&intel_dp->aux, DP_SUPPORTED_LINK_RATES, > - sink_rates, sizeof(sink_rates)); > + ret = drm_dp_dpcd_read_data(&intel_dp->aux, > + DP_SUPPORTED_LINK_RATES, > + sink_rates, sizeof(sink_rates)); > + if (ret < 0) { > + drm_dbg_kms(display->drm, > + "Unable to read eDP supported link rates, using default rates\n"); > + memset(sink_rates, 0, sizeof(sink_rates)); > + } > > for (i = 0; i < ARRAY_SIZE(sink_rates); i++) { > int rate; -- Jani Nikula, Intel