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[23.128.96.18]) by mx.google.com with ESMTP id j1si17287913plr.385.2021.10.18.07.02.51; Mon, 18 Oct 2021 07:03:07 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=Ah3bkGoH; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234431AbhJROCX (ORCPT + 99 others); Mon, 18 Oct 2021 10:02:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:41920 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234519AbhJROAY (ORCPT ); Mon, 18 Oct 2021 10:00:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4206461353; Mon, 18 Oct 2021 13:42:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1634564536; bh=SyN04pPK4PBEiS8Av1SoZaec2ubE95+27Hq9MKHlG14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ah3bkGoHCdN871P1QBYcIINPbR/WCDAETufW2FxbwRdMs95Y6kGHRFQwlEuWqE0oo g0s0hWCaj67EuwLXIwnTwizJFYsM2x2w7SJzWAEsnyS7/ZC9gduA7trfwJZppbfmjL axFJjR20VRiCHY6ocpsHyAUfoeIFn7u40m4pBIxs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Douglas Anderson , Dave Airlie Subject: [PATCH 5.14 126/151] drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read Date: Mon, 18 Oct 2021 15:25:05 +0200 Message-Id: <20211018132344.770075577@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211018132340.682786018@linuxfoundation.org> References: <20211018132340.682786018@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Douglas Anderson commit 97794170b696856483f74b47bfb6049780d2d3a0 upstream. In commit e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid corruption test") the function connector_bad_edid() started assuming that the memory for the EDID passed to it was big enough to hold `edid[0x7e] + 1` blocks of data (1 extra for the base block). It completely ignored the fact that the function was passed `num_blocks` which indicated how much memory had been allocated for the EDID. Let's fix this by adding a bounds check. This is important for handling the case where there's an error in the first block of the EDID. In that case we will call connector_bad_edid() without having re-allocated memory based on `edid[0x7e]`. Fixes: e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid corruption test") Reported-by: Ville Syrjälä Signed-off-by: Douglas Anderson Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20211005192905.v2.1.Ib059f9c23c2611cb5a9d760e7d0a700c1295928d@changeid Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_edid.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1834,11 +1834,20 @@ static void connector_bad_edid(struct dr u8 *edid, int num_blocks) { int i; - u8 num_of_ext = edid[0x7e]; + u8 last_block; + + /* + * 0x7e in the EDID is the number of extension blocks. The EDID + * is 1 (base block) + num_ext_blocks big. That means we can think + * of 0x7e in the EDID of the _index_ of the last block in the + * combined chunk of memory. + */ + last_block = edid[0x7e]; /* Calculate real checksum for the last edid extension block data */ - connector->real_edid_checksum = - drm_edid_block_checksum(edid + num_of_ext * EDID_LENGTH); + if (last_block < num_blocks) + connector->real_edid_checksum = + drm_edid_block_checksum(edid + last_block * EDID_LENGTH); if (connector->bad_edid_counter++ && !drm_debug_enabled(DRM_UT_KMS)) return;