From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60696 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752558AbcEAXUY (ORCPT ); Sun, 1 May 2016 19:20:24 -0400 Subject: Patch "drm/dp/mst: Validate port in drm_dp_payload_send_msg()" has been added to the 4.5-stable tree To: cpaul@redhat.com, airlied@linux.ie, airlied@redhat.com, gregkh@linuxfoundation.org Cc: , From: Date: Sun, 01 May 2016 16:20:23 -0700 Message-ID: <1462144823134254@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled drm/dp/mst: Validate port in drm_dp_payload_send_msg() to the 4.5-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-dp-mst-validate-port-in-drm_dp_payload_send_msg.patch and it can be found in the queue-4.5 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From deba0a2af9592b2022a0bce7b085a318b53ce1db Mon Sep 17 00:00:00 2001 From: "cpaul@redhat.com" Date: Mon, 4 Apr 2016 19:58:47 -0400 Subject: drm/dp/mst: Validate port in drm_dp_payload_send_msg() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: cpaul@redhat.com commit deba0a2af9592b2022a0bce7b085a318b53ce1db upstream. With the joys of things running concurrently, there's always a chance that the port we get passed in drm_dp_payload_send_msg() isn't actually valid anymore. Because of this, we need to make sure we validate the reference to the port before we use it otherwise we risk running into various race conditions. For instance, on the Dell MST monitor I have here for testing, hotplugging it enough times causes us to kernel panic: [drm:intel_mst_enable_dp] 1 [drm:drm_dp_update_payload_part2] payload 0 1 [drm:intel_get_hpd_pins] hotplug event received, stat 0x00200000, dig 0x10101011, pins 0x00000020 [drm:intel_hpd_irq_handler] digital hpd port B - short [drm:intel_dp_hpd_pulse] got hpd irq on port B - short [drm:intel_dp_check_mst_status] got esi 00 10 00 [drm:drm_dp_update_payload_part2] payload 1 1 general protection fault: 0000 [#1] SMP … Call Trace: [] drm_dp_update_payload_part2+0xc2/0x130 [drm_kms_helper] [] intel_mst_enable_dp+0xf8/0x180 [i915] [] haswell_crtc_enable+0x3ed/0x8c0 [i915] [] intel_atomic_commit+0x5ad/0x1590 [i915] [] ? drm_atomic_set_crtc_for_connector+0x57/0xe0 [drm] [] drm_atomic_commit+0x37/0x60 [drm] [] drm_atomic_helper_set_config+0x7a/0xb0 [drm_kms_helper] [] drm_mode_set_config_internal+0x62/0x100 [drm] [] drm_mode_setcrtc+0x3cd/0x4e0 [drm] [] drm_ioctl+0x143/0x510 [drm] [] ? drm_mode_setplane+0x1b0/0x1b0 [drm] [] ? hrtimer_start_range_ns+0x1b7/0x3a0 [] do_vfs_ioctl+0x92/0x570 [] ? __sys_recvmsg+0x42/0x80 [] SyS_ioctl+0x79/0x90 [] entry_SYSCALL_64_fastpath+0x1a/0xa4 RIP [] drm_dp_payload_send_msg+0x146/0x1f0 [drm_kms_helper] Which occurs because of the hotplug event shown in the log, which ends up causing DRM's dp helpers to drop the port we're updating the payload on and panic. Signed-off-by: Lyude Reviewed-by: David Airlie Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_mst_topology.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1672,13 +1672,19 @@ static int drm_dp_payload_send_msg(struc u8 sinks[DRM_DP_MAX_SDP_STREAMS]; int i; + port = drm_dp_get_validated_port_ref(mgr, port); + if (!port) + return -EINVAL; + port_num = port->port_num; mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent); if (!mstb) { mstb = drm_dp_get_last_connected_port_and_mstb(mgr, port->parent, &port_num); - if (!mstb) + if (!mstb) { + drm_dp_put_port(port); return -EINVAL; + } } txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL); @@ -1707,6 +1713,7 @@ static int drm_dp_payload_send_msg(struc kfree(txmsg); fail_put: drm_dp_put_mst_branch_device(mstb); + drm_dp_put_port(port); return ret; } Patches currently in stable-queue which might be from cpaul@redhat.com are queue-4.5/drm-dp-mst-restore-primary-hub-guid-on-resume.patch queue-4.5/drm-dp-mst-validate-port-in-drm_dp_payload_send_msg.patch queue-4.5/drm-i915-fix-race-condition-in-intel_dp_destroy_mst_connector.patch queue-4.5/drm-dp-mst-get-validated-port-ref-in-drm_dp_update_payload_part1.patch