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 6F9EBC4332F for ; Mon, 6 Nov 2023 13:24:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232514AbjKFNYI (ORCPT ); Mon, 6 Nov 2023 08:24:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232498AbjKFNYF (ORCPT ); Mon, 6 Nov 2023 08:24:05 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33C0CEA for ; Mon, 6 Nov 2023 05:24:03 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77463C433C9; Mon, 6 Nov 2023 13:24:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1699277042; bh=B24K2oF8uAXS5j/RYIiryPmr0dxiobaVc+UjJxVGYaQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=19AcFtU/ncdfEGY0SViigcYbbxSz+3ad/WsCwlHCbssHLxiOC02YLfmpmUDl9OeAy au0GLTtsolEjEuU7QPmKkKnB2iUaaNHTPybftgSoZSaZCZACoJqfBcv2uNY7iNBwxl wIxdGtDwiii+FDD9LErXVTtHC8XeO0RBgL4kLtug= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lukasz Majczak , Radoslaw Biernacki , Manasi Navare , Sasha Levin Subject: [PATCH 5.15 019/128] drm/dp_mst: Fix NULL deref in get_mst_branch_device_by_guid_helper() Date: Mon, 6 Nov 2023 14:02:59 +0100 Message-ID: <20231106130310.001708155@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231106130309.112650042@linuxfoundation.org> References: <20231106130309.112650042@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukasz Majczak [ Upstream commit 3d887d512494d678b17c57b835c32f4e48d34f26 ] 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: Sasha Levin --- drivers/gpu/drm/drm_dp_mst_topology.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index d02e323a4ecde..865c7f39143ec 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2615,14 +2615,14 @@ static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper( 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) -- 2.42.0