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 260D3E99046 for ; Fri, 10 Apr 2026 07:06:51 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0585E10E899; Fri, 10 Apr 2026 07:06:50 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="pgi5chsd"; dkim-atps=neutral Received: from mail-qv1-f45.google.com (mail-qv1-f45.google.com [209.85.219.45]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6414310E05A for ; Fri, 10 Apr 2026 04:00:35 +0000 (UTC) Received: by mail-qv1-f45.google.com with SMTP id 6a1803df08f44-8a151012558so19035766d6.3 for ; Thu, 09 Apr 2026 21:00:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775793634; x=1776398434; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=40je6pyvB78AE8C7RBxzyLMhGBsBo98AwoJUcXd6tRE=; b=pgi5chsdJATFJTtfOQ7Mynm7/sOCSTi80ZijeVE3An8HWZOAxERrXLIPt0COuS/M+m t/oC9hQE3AHOFffKx7gzjqm55grEj5Rnpcy8TM2tuw7ESHWUyY9EyG1IAm1pHN7trvnd LdRrH2fL8dqgCfLBwUTCjQQAcM7bWQ51H5wea0fSiaI3XTa4gBYkM8CXblNaND/tpWZq QnpcNgAVc08IFYtMOR2biyrEW1js4s2yDjr8TmufpGpnKVMUWX4gYMPahjrXKAF7ACkI whweVKyA1rxqwM3G+R17qvm4OsU8W+VgbvJphI5uQyTjmaxQpJxt9RSS1a5mWS4dTqUU nFEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775793634; x=1776398434; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=40je6pyvB78AE8C7RBxzyLMhGBsBo98AwoJUcXd6tRE=; b=IqTL1XQTtbExQI2nc3F/uKMIsOgJrNJY4cyY1o36Y6eKoQG677PBxLHBIHlelhASDH b4X28EL/Mv3PhuJswriukiNc8VZOdDefZxE1748hVLkRZlQaRlYREU2qxqYZ5vtYYiKd dxw4U0BRoagRE39fuAJ/zpy9uxaWaZOHFl/R+m34sGSnHj4IDWub72KgimHN84mRqoMd XcPgE42Ro0FurhnbTQ3b/qi3lGreI5f2gdkoBGpdFwIeIbDFqmCGQYWnaz4lQHgRlk/i xY9+lwDEsHx4nEpTj+76eBfVJFyd258+RESWs1CBNwzQWvwkh80gFbNuUEr0WKbNLdqS /brw== X-Gm-Message-State: AOJu0YyelXJ9LQd6+CvOvHcKSrETp0JAJQWEYkH9kg8Gz77oJHmnuU+B Ic56fV6dCY9+FW5xYFr8zFEhdPIBcltQy10M9scurENNxnyQ/b7vP1z8gjI2ZbwWvBrR0g== X-Gm-Gg: AeBDietmcHIdxgsPPfdPP5PGltJt4RcOTqmTj6wUF19XTZiGT4f2mqHDTujQNfG8h9w 7sLjgGYkWOTpor44hF4worztKQC5GUfJzYaJLGe/ZauS8hWAHAyn7VtNhoQtC3iA00LOsgNrHHn oc0QLZIL5OdD+5zdj1r2f5vwYS6G/07xNZkBO47bQqOLxr/QmK4PLUK7ApMhoNb4TSrOtzLYi0N 6G/+OsBYUk+i13VFIHWfTidsH8tMiQmrQhZPQ+ZHsJ4RWbW9iGjOKHjmwosmfK+enaCYbZ25D85 5eQkVD9U5kmQGUB+1lwUDXjYBd24dpLZI/rr9lliRWhrcOsZU05DA4q+8JXIpp9buNmsHJtIJKS MzVrJPJVTnW7GvwG1iWHoVqcg/EPjyTds9LcT7LnMXV/4ZOkNLw/SdSXEzLlmbv+6WwpktfpO1b 3M1Mbes1BFxLoOheJug9uXG1thmhYfaUuAONHMAwtaZqTCff3Upb9iyGC3hwMSEl/V+RrSVAHhv Mn4nxGvgrk25vw8h5hB9s7fYxNM X-Received: by 2002:a05:6214:c4e:b0:8ac:8938:ee55 with SMTP id 6a1803df08f44-8ac893902e8mr7757046d6.11.1775793634061; Thu, 09 Apr 2026 21:00:34 -0700 (PDT) Received: from TDC4045031631.e0cglfehwr0e5gttmepj3hi3hf.ux.internal.cloudapp.net ([20.63.37.123]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac84cdda1csm14132946d6.43.2026.04.09.21.00.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2026 21:00:33 -0700 (PDT) From: Ashutosh Desai To: dri-devel@lists.freedesktop.org Cc: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, linux-kernel@vger.kernel.org, Ashutosh Desai Subject: [PATCH] drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers Date: Fri, 10 Apr 2026 04:00:26 +0000 Message-Id: <20260410040026.2436280-1-ashutoshdesai993@gmail.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Fri, 10 Apr 2026 07:06:48 +0000 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" Three sideband reply parsers read 16-bit fields as: val = (raw->msg[idx] << 8) | (raw->msg[idx+1]); and only check bounds after the fact (idx += 2, then if (idx > raw->curlen)). When idx == raw->curlen at the point of the read, raw->msg[idx+1] is one byte past the received message data, reading into the following struct fields (curchunk_len, curchunk_idx, curlen). Affected functions: - drm_dp_sideband_parse_enum_path_resources_ack() full_payload_bw_number and avail_payload_bw_number fields - drm_dp_sideband_parse_allocate_payload_ack() allocated_pbn field - drm_dp_sideband_parse_query_payload_ack() allocated_pbn field Move the bounds check to immediately before each 2-byte read, using idx + 2 > raw->curlen, consistent with the fix pattern used elsewhere in this file. Signed-off-by: Ashutosh Desai --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 9cef6c576..f2a7dbc5e 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -931,14 +931,13 @@ static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband idx++; if (idx > raw->curlen) goto fail_len; + if (idx + 2 > raw->curlen) + goto fail_len; repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]); idx += 2; - if (idx > raw->curlen) + if (idx + 2 > raw->curlen) goto fail_len; repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]); - idx += 2; - if (idx > raw->curlen) - goto fail_len; return true; fail_len: DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen); @@ -958,10 +957,9 @@ static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_ms idx++; if (idx > raw->curlen) goto fail_len; - repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]); - idx += 2; - if (idx > raw->curlen) + if (idx + 2 > raw->curlen) goto fail_len; + repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]); return true; fail_len: DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen); @@ -977,10 +975,9 @@ static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_r idx++; if (idx > raw->curlen) goto fail_len; - repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]); - idx += 2; - if (idx > raw->curlen) + if (idx + 2 > raw->curlen) goto fail_len; + repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]); return true; fail_len: DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen); -- 2.34.1