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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79020C433E1 for ; Fri, 21 Aug 2020 17:35:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 49F6820658 for ; Fri, 21 Aug 2020 17:35:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="pKSo1Jla" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 49F6820658 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=crudebyte.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39100 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k9AxE-0004RY-Fa for qemu-devel@archiver.kernel.org; Fri, 21 Aug 2020 13:35:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58570) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k9AwE-0002dH-LS for qemu-devel@nongnu.org; Fri, 21 Aug 2020 13:34:50 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:40293) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k9AwC-0001se-AS for qemu-devel@nongnu.org; Fri, 21 Aug 2020 13:34:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Content-ID:Content-Description; bh=J1ilFJOxYvVYcefj0wsxykyOcvukBanOEpKQEzYo0lM=; b=pKSo1JlaATA7z/10G2VPysZME2 GWs886YaAtwFGh5q90nbgAGe4YT9IXWn1fairDXXNfK6RNBWwmgOz0VWq12i0ha4hBTjPjSFAuwdz w907LuoOZj/muf0j1feUhTjFpw+dYSkoHYzlTxN/8hx8GKSlcEWg4W7mxOpQ2Rj/F2Wua/2WaEDGA DtvWCKHmxnFQVsrbCwLzGhyAu8Z3LEXtdTjnR27cRJyEUH2tQ/TK3pwCray3g+3wwjbPTQ8XrVbOC T1eliNLeYFMEh4Fzzf/F7ObXIujrV0cxErC1jIRN3NZPrTBmjiml0/ynD8i8uv/BlwYGKz9VOiEJR xqlsXL0Q==; From: Christian Schoenebeck To: qemu-devel@nongnu.org Cc: Geoffrey McRae , kraxel@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH v8 1/1] audio/jack: fix use after free segfault Date: Fri, 21 Aug 2020 19:34:44 +0200 Message-ID: <3291053.UyeazdVyI9@silver> In-Reply-To: <20200821134554.101397-2-geoff@hostfission.com> References: <20200821134554.101397-1-geoff@hostfission.com> <20200821134554.101397-2-geoff@hostfission.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Received-SPF: pass client-ip=91.194.90.13; envelope-from=qemu_oss@crudebyte.com; helo=lizzy.crudebyte.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/21 13:34:46 X-ACL-Warn: Detected OS = Linux 3.11 and newer X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Freitag, 21. August 2020 15:45:54 CEST Geoffrey McRae wrote: > This change registers a bottom handler to close the JACK client > connection when a server shutdown signal is recieved. Without this > libjack2 attempts to "clean up" old clients and causes a use after free > segfault. > > Signed-off-by: Geoffrey McRae > --- > audio/jackaudio.c | 55 ++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 42 insertions(+), 13 deletions(-) > > diff --git a/audio/jackaudio.c b/audio/jackaudio.c > index 72ed7c4929..572ebea208 100644 > --- a/audio/jackaudio.c > +++ b/audio/jackaudio.c > @@ -25,6 +25,7 @@ > #include "qemu/osdep.h" > #include "qemu/module.h" > #include "qemu/atomic.h" > +#include "qemu/main-loop.h" > #include "qemu-common.h" > #include "audio.h" > > @@ -63,6 +64,8 @@ typedef struct QJackClient { > QJackState state; > jack_client_t *client; > jack_nframes_t freq; > + QemuMutex shutdown_lock; > + QEMUBH *shutdown_bh; > > struct QJack *j; > int nchannels; > @@ -306,21 +309,27 @@ static int qjack_xrun(void *arg) > return 0; > } > > +static void qjack_shutdown_bh(void *opaque) > +{ > + QJackClient *c = (QJackClient *)opaque; > + qjack_client_fini(c); > +} > + > static void qjack_shutdown(void *arg) > { > QJackClient *c = (QJackClient *)arg; > c->state = QJACK_STATE_SHUTDOWN; > + qemu_bh_schedule(c->shutdown_bh); > } > > static void qjack_client_recover(QJackClient *c) > { > - if (c->state == QJACK_STATE_SHUTDOWN) { > - qjack_client_fini(c); > + if (c->state != QJACK_STATE_DISCONNECTED) { > + return; > } > > /* packets is used simply to throttle this */ > - if (c->state == QJACK_STATE_DISCONNECTED && > - c->packets % 100 == 0) { > + if (c->packets % 100 == 0) { > > /* if enabled then attempt to recover */ > if (c->enabled) { > @@ -489,15 +498,18 @@ static int qjack_init_out(HWVoiceOut *hw, struct > audsettings *as, QJackOut *jo = (QJackOut *)hw; > Audiodev *dev = (Audiodev *)drv_opaque; > > - qjack_client_fini(&jo->c); > - > jo->c.out = true; > jo->c.enabled = false; > jo->c.nchannels = as->nchannels; > jo->c.opt = dev->u.jack.out; > > + jo->c.shutdown_bh = qemu_bh_new(qjack_shutdown_bh, &jo->c); > + qemu_mutex_init(&jo->c.shutdown_lock); > + > int ret = qjack_client_init(&jo->c); > if (ret != 0) { > + qemu_bh_delete(jo->c.shutdown_bh); > + qemu_mutex_destroy(&jo->c.shutdown_lock); > return ret; > } > > @@ -525,15 +537,18 @@ static int qjack_init_in(HWVoiceIn *hw, struct > audsettings *as, QJackIn *ji = (QJackIn *)hw; > Audiodev *dev = (Audiodev *)drv_opaque; > > - qjack_client_fini(&ji->c); > - > ji->c.out = false; > ji->c.enabled = false; > ji->c.nchannels = as->nchannels; > ji->c.opt = dev->u.jack.in; > > + ji->c.shutdown_bh = qemu_bh_new(qjack_shutdown_bh, &ji->c); > + qemu_mutex_init(&ji->c.shutdown_lock); > + > int ret = qjack_client_init(&ji->c); > if (ret != 0) { > + qemu_bh_delete(ji->c.shutdown_bh); > + qemu_mutex_destroy(&ji->c.shutdown_lock); > return ret; > } > > @@ -555,7 +570,7 @@ static int qjack_init_in(HWVoiceIn *hw, struct > audsettings *as, return 0; > } > > -static void qjack_client_fini(QJackClient *c) > +static void qjack_client_fini_locked(QJackClient *c) > { > switch (c->state) { > case QJACK_STATE_RUNNING: > @@ -564,28 +579,42 @@ static void qjack_client_fini(QJackClient *c) > > case QJACK_STATE_SHUTDOWN: > jack_client_close(c->client); > + c->client = NULL; > + > + qjack_buffer_free(&c->fifo); > + g_free(c->port); > + > + c->state = QJACK_STATE_DISCONNECTED; > /* fallthrough */ > > case QJACK_STATE_DISCONNECTED: > break; > } > +} > > - qjack_buffer_free(&c->fifo); > - g_free(c->port); > - > - c->state = QJACK_STATE_DISCONNECTED; > +static void qjack_client_fini(QJackClient *c) > +{ > + qemu_mutex_lock(&c->shutdown_lock); > + qjack_client_fini_locked(c); > + qemu_mutex_unlock(&c->shutdown_lock); > } > > static void qjack_fini_out(HWVoiceOut *hw) > { > QJackOut *jo = (QJackOut *)hw; > qjack_client_fini(&jo->c); > + > + qemu_bh_delete(jo->c.shutdown_bh); Paolo wrapped that qemu_bh_delete() call inside the lock as well. So I guess it makes a difference for the BH API? > + qemu_mutex_destroy(&jo->c.shutdown_lock); > } Hmmm, is this qemu_mutex_destroy() safe at this point? > > static void qjack_fini_in(HWVoiceIn *hw) > { > QJackIn *ji = (QJackIn *)hw; > qjack_client_fini(&ji->c); > + > + qemu_bh_delete(ji->c.shutdown_bh); > + qemu_mutex_destroy(&ji->c.shutdown_lock); > } > > static void qjack_enable_out(HWVoiceOut *hw, bool enable) Best regards, Christian Schoenebeck