From patchwork Tue Jan 29 18:39:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 10786861 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E79371399 for ; Tue, 29 Jan 2019 18:39:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D6D7D2931E for ; Tue, 29 Jan 2019 18:39:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CAEC42D2B8; Tue, 29 Jan 2019 18:39:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5080E2931E for ; Tue, 29 Jan 2019 18:39:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C5C5F6E924; Tue, 29 Jan 2019 18:39:41 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTPS id 94A366E924; Tue, 29 Jan 2019 18:39:39 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 268EF51EF3; Tue, 29 Jan 2019 18:39:39 +0000 (UTC) Received: from malachite.bss.redhat.com (dhcp-10-20-1-11.bss.redhat.com [10.20.1.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id 067F51713D; Tue, 29 Jan 2019 18:39:32 +0000 (UTC) From: Lyude Paul To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Date: Tue, 29 Jan 2019 13:39:25 -0500 Message-Id: <20190129183928.26779-2-lyude@redhat.com> In-Reply-To: <20190129183928.26779-1-lyude@redhat.com> References: <20190129183928.26779-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 29 Jan 2019 18:39:39 +0000 (UTC) Subject: [Intel-gfx] [PATCH 1/3] drm/dp_mst: Fix unbalanced malloc ref in drm_dp_mst_deallocate_vcpi() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maxime Ripard , linux-kernel@vger.kernel.org, David Airlie Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP In drm_dp_mst_deallocate_vcpi(), we currently unconditionally call drm_dp_mst_put_port_malloc() on the port that's passed to us, even if we never successfully allocated VCPI to it. This is contrary to what we do in drm_dp_mst_allocate_vcpi(), where we only call drm_dp_mst_get_port_malloc() on the passed port if we successfully allocated VCPI to it. As a result, if drm_dp_mst_allocate_vcpi() fails during a modeset and another successive modeset calls drm_dp_mst_deallocate_vcpi() we will end up dropping someone else's malloc reference to the port. Example: [ 962.309260] ================================================================== [ 962.309290] BUG: KASAN: use-after-free in drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309296] Read of size 4 at addr ffff888416c30004 by task kworker/0:1H/500 [ 962.309308] CPU: 0 PID: 500 Comm: kworker/0:1H Tainted: G W O 5.0.0-rc2Lyude-Test+ #1 [ 962.309313] Hardware name: LENOVO 20L8S2N800/20L8S2N800, BIOS N22ET35W (1.12 ) 04/09/2018 [ 962.309428] Workqueue: events_highpri intel_atomic_cleanup_work [i915] [ 962.309434] Call Trace: [ 962.309452] dump_stack+0xad/0x150 [ 962.309462] ? dump_stack_print_info.cold.0+0x1b/0x1b [ 962.309472] ? kmsg_dump_rewind_nolock+0xd9/0xd9 [ 962.309504] ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309515] print_address_description+0x6c/0x23c [ 962.309542] ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309568] ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309577] kasan_report.cold.3+0x1a/0x32 [ 962.309605] ? drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309631] drm_dp_mst_put_port_malloc+0x72/0x180 [drm_kms_helper] [ 962.309658] ? drm_dp_mst_put_mstb_malloc+0x180/0x180 [drm_kms_helper] [ 962.309687] drm_dp_mst_destroy_state+0xcd/0x120 [drm_kms_helper] [ 962.309745] drm_atomic_state_default_clear+0x6ee/0xcc0 [drm] [ 962.309864] intel_atomic_state_clear+0xe/0x80 [i915] [ 962.309928] __drm_atomic_state_free+0x35/0xd0 [drm] [ 962.310044] intel_atomic_cleanup_work+0x56/0x70 [i915] [ 962.310057] process_one_work+0x884/0x1400 [ 962.310067] ? drain_workqueue+0x5a0/0x5a0 [ 962.310075] ? __schedule+0x87f/0x1e80 [ 962.310086] ? __sched_text_start+0x8/0x8 [ 962.310095] ? run_rebalance_domains+0x400/0x400 [ 962.310110] ? deref_stack_reg+0xb4/0x120 [ 962.310117] ? __read_once_size_nocheck.constprop.7+0x10/0x10 [ 962.310124] ? worker_enter_idle+0x47f/0x6a0 [ 962.310134] ? schedule+0xd7/0x2e0 [ 962.310141] ? __schedule+0x1e80/0x1e80 [ 962.310148] ? _raw_spin_lock_irq+0x9f/0x130 [ 962.310155] ? _raw_write_unlock_irqrestore+0x110/0x110 [ 962.310164] worker_thread+0x196/0x11e0 [ 962.310175] ? set_load_weight+0x2e0/0x2e0 [ 962.310181] ? __switch_to_asm+0x34/0x70 [ 962.310187] ? __switch_to_asm+0x40/0x70 [ 962.310194] ? process_one_work+0x1400/0x1400 [ 962.310199] ? __switch_to_asm+0x40/0x70 [ 962.310205] ? __switch_to_asm+0x34/0x70 [ 962.310211] ? __switch_to_asm+0x34/0x70 [ 962.310216] ? __switch_to_asm+0x40/0x70 [ 962.310221] ? __switch_to_asm+0x34/0x70 [ 962.310226] ? __switch_to_asm+0x40/0x70 [ 962.310231] ? __switch_to_asm+0x34/0x70 [ 962.310236] ? __switch_to_asm+0x40/0x70 [ 962.310242] ? syscall_return_via_sysret+0xf/0x7f [ 962.310248] ? __switch_to_asm+0x34/0x70 [ 962.310253] ? __switch_to_asm+0x40/0x70 [ 962.310258] ? __switch_to_asm+0x34/0x70 [ 962.310263] ? __switch_to_asm+0x40/0x70 [ 962.310268] ? __switch_to_asm+0x34/0x70 [ 962.310273] ? __switch_to_asm+0x40/0x70 [ 962.310281] ? __schedule+0x87f/0x1e80 [ 962.310292] ? __sched_text_start+0x8/0x8 [ 962.310300] ? save_stack+0x8c/0xb0 [ 962.310308] ? __kasan_kmalloc.constprop.6+0xc6/0xd0 [ 962.310313] ? kthread+0x98/0x3a0 [ 962.310318] ? ret_from_fork+0x35/0x40 [ 962.310334] ? __wake_up_common+0x178/0x6f0 [ 962.310343] ? _raw_spin_lock_irqsave+0xa4/0x140 [ 962.310349] ? __lock_text_start+0x8/0x8 [ 962.310355] ? _raw_write_lock_irqsave+0x70/0x130 [ 962.310360] ? __lock_text_start+0x8/0x8 [ 962.310371] ? process_one_work+0x1400/0x1400 [ 962.310376] kthread+0x2e2/0x3a0 [ 962.310383] ? kthread_create_on_node+0xc0/0xc0 [ 962.310389] ret_from_fork+0x35/0x40 [ 962.310401] Allocated by task 1462: [ 962.310410] __kasan_kmalloc.constprop.6+0xc6/0xd0 [ 962.310437] drm_dp_add_port+0xd60/0x1960 [drm_kms_helper] [ 962.310464] drm_dp_send_link_address+0x4b0/0x770 [drm_kms_helper] [ 962.310491] drm_dp_check_and_send_link_address+0x197/0x1f0 [drm_kms_helper] [ 962.310515] drm_dp_mst_link_probe_work+0x2b6/0x330 [drm_kms_helper] [ 962.310522] process_one_work+0x884/0x1400 [ 962.310529] worker_thread+0x196/0x11e0 [ 962.310533] kthread+0x2e2/0x3a0 [ 962.310538] ret_from_fork+0x35/0x40 [ 962.310543] Freed by task 500: [ 962.310550] __kasan_slab_free+0x133/0x180 [ 962.310555] kfree+0x92/0x1a0 [ 962.310581] drm_dp_mst_put_port_malloc+0x14d/0x180 [drm_kms_helper] [ 962.310693] intel_connector_destroy+0xb2/0xe0 [i915] [ 962.310747] drm_mode_object_put.part.0+0x12b/0x1a0 [drm] [ 962.310802] drm_atomic_state_default_clear+0x1f2/0xcc0 [drm] [ 962.310916] intel_atomic_state_clear+0xe/0x80 [i915] [ 962.310972] __drm_atomic_state_free+0x35/0xd0 [drm] [ 962.311083] intel_atomic_cleanup_work+0x56/0x70 [i915] [ 962.311092] process_one_work+0x884/0x1400 [ 962.311098] worker_thread+0x196/0x11e0 [ 962.311103] kthread+0x2e2/0x3a0 [ 962.311108] ret_from_fork+0x35/0x40 [ 962.311116] The buggy address belongs to the object at ffff888416c30000 which belongs to the cache kmalloc-2k of size 2048 [ 962.311122] The buggy address is located 4 bytes inside of 2048-byte region [ffff888416c30000, ffff888416c30800) [ 962.311124] The buggy address belongs to the page: [ 962.311132] page:ffffea00105b0c00 count:1 mapcount:0 mapping:ffff88841d003040 index:0x0 compound_mapcount: 0 [ 962.311142] flags: 0x8000000000010200(slab|head) [ 962.311152] raw: 8000000000010200 dead000000000100 dead000000000200 ffff88841d003040 [ 962.311159] raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000 [ 962.311162] page dumped because: kasan: bad access detected So, bail early if drm_dp_mst_deallocate_vcpi() is called on a port with no VCPI allocation. Additionally, clean up the surrounding kerneldoc while we're at it since the port is assumed to be kept around because the DRM driver is expected to hold a malloc reference to it, not just us. Signed-off-by: Lyude Paul Fixes: eceae1472467 ("drm/dp_mst: Start tracking per-port VCPI allocations") Cc: Daniel Vetter Reviewed-by: Daniel Vetter --- drivers/gpu/drm/drm_dp_mst_topology.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 2552a27362a0..8ba0e5b368da 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3246,15 +3246,13 @@ EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots); /** * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI * @mgr: manager for this port - * @port: unverified port to deallocate vcpi for + * @port: port to deallocate vcpi for */ void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port) { - /* - * A port with VCPI will remain allocated until it's VCPI is - * released, no verified ref needed - */ + if (!port->vcpi.vcpi) + return; drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi); port->vcpi.num_slots = 0;