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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C992FC4332F for ; Mon, 6 Nov 2023 13:21:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232377AbjKFNVH (ORCPT ); Mon, 6 Nov 2023 08:21:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232395AbjKFNVG (ORCPT ); Mon, 6 Nov 2023 08:21:06 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 317A2112 for ; Mon, 6 Nov 2023 05:21:03 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C869C433C7; Mon, 6 Nov 2023 13:21:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1699276862; bh=JVb64qR6iBziCKYdz7WDSD9S+Yjv6Uncg5X+pHvT5Ck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SXOCzrafaU+wfFq/g3QfRXHsTsDOtbNqi7gmlGkLNRqPsz7Sbk47KbRPbYQPIYEbf 4fCyPsSKSN3dRWx2Ax2PZfsiMqWiWsNYDzzApXrkr2vHHoL5fYl5VGr3/WKl9JVR9K wiBN4Q8hPqNWCsi/FH2CmIxwyRuLfcidpi3M9hmk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lukasz Majczak , Radoslaw Biernacki , Manasi Navare Subject: [PATCH 5.4 33/74] drm/dp_mst: Fix NULL deref in get_mst_branch_device_by_guid_helper() Date: Mon, 6 Nov 2023 14:03:53 +0100 Message-ID: <20231106130302.899297439@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231106130301.687882731@linuxfoundation.org> References: <20231106130301.687882731@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukasz Majczak commit 3d887d512494d678b17c57b835c32f4e48d34f26 upstream. As drm_dp_get_mst_branch_device_by_guid() is called from drm_dp_get_mst_branch_device_by_guid(), mstb parameter has to be checked, otherwise NULL dereference may occur in the call to the memcpy() and cause following: [12579.365869] BUG: kernel NULL pointer dereference, address: 0000000000000049 [12579.365878] #PF: supervisor read access in kernel mode [12579.365880] #PF: error_code(0x0000) - not-present page [12579.365882] PGD 0 P4D 0 [12579.365887] Oops: 0000 [#1] PREEMPT SMP NOPTI ... [12579.365895] Workqueue: events_long drm_dp_mst_up_req_work [12579.365899] RIP: 0010:memcmp+0xb/0x29 [12579.365921] Call Trace: [12579.365927] get_mst_branch_device_by_guid_helper+0x22/0x64 [12579.365930] drm_dp_mst_up_req_work+0x137/0x416 [12579.365933] process_one_work+0x1d0/0x419 [12579.365935] worker_thread+0x11a/0x289 [12579.365938] kthread+0x13e/0x14f [12579.365941] ? process_one_work+0x419/0x419 [12579.365943] ? kthread_blkcg+0x31/0x31 [12579.365946] ret_from_fork+0x1f/0x30 As get_mst_branch_device_by_guid_helper() is recursive, moving condition to the first line allow to remove a similar one for step over of NULL elements inside a loop. Fixes: 5e93b8208d3c ("drm/dp/mst: move GUID storage from mgr, port to only mst branch") Cc: # 4.14+ Signed-off-by: Lukasz Majczak Reviewed-by: Radoslaw Biernacki Signed-off-by: Manasi Navare Link: https://patchwork.freedesktop.org/patch/msgid/20230922063410.23626-1-lma@semihalf.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_mst_topology.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1806,14 +1806,14 @@ static struct drm_dp_mst_branch *get_mst struct drm_dp_mst_branch *found_mstb; struct drm_dp_mst_port *port; + if (!mstb) + return NULL; + if (memcmp(mstb->guid, guid, 16) == 0) return mstb; list_for_each_entry(port, &mstb->ports, next) { - if (!port->mstb) - continue; - found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid); if (found_mstb)