From patchwork Mon Mar 7 22:47:26 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 593534 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 7D4C514029E; Tue, 8 Mar 2016 09:54:07 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ad42P-00008l-Bb; Mon, 07 Mar 2016 22:54:05 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad40p-0007Qw-Fx for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:52:27 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad40p-00009T-1l; Mon, 07 Mar 2016 22:52:27 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad40m-0001tb-By; Mon, 07 Mar 2016 14:52:24 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 4.2.y-ckt 055/273] ALSA: seq: Fix yet another races among ALSA timer accesses Date: Mon, 7 Mar 2016 14:47:26 -0800 Message-Id: <1457391064-6660-56-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457391064-6660-1-git-send-email-kamal@canonical.com> References: <1457391064-6660-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Cc: Takashi Iwai , Kamal Mostafa X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Takashi Iwai commit 2cdc7b636d55cbcf42e1e6c8accd85e62d3e9ae8 upstream. ALSA sequencer may open/close and control ALSA timer instance dynamically either via sequencer events or direct ioctls. These are done mostly asynchronously, and it may call still some timer action like snd_timer_start() while another is calling snd_timer_close(). Since the instance gets removed by snd_timer_close(), it may lead to a use-after-free. This patch tries to address such a race by protecting each snd_timer_*() call via the existing spinlock and also by avoiding the access to timer during close call. BugLink: http://lkml.kernel.org/r/CACT4Y+Z6RzW5MBr-HUdV-8zwg71WQfKTdPpYGvOeS7v4cyurNQ@mail.gmail.com Reported-by: Dmitry Vyukov Signed-off-by: Takashi Iwai Signed-off-by: Kamal Mostafa --- sound/core/seq/seq_timer.c | 87 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 67 insertions(+), 20 deletions(-) diff --git a/sound/core/seq/seq_timer.c b/sound/core/seq/seq_timer.c index 82b220c..2931049 100644 --- a/sound/core/seq/seq_timer.c +++ b/sound/core/seq/seq_timer.c @@ -90,6 +90,9 @@ void snd_seq_timer_delete(struct snd_seq_timer **tmr) void snd_seq_timer_defaults(struct snd_seq_timer * tmr) { + unsigned long flags; + + spin_lock_irqsave(&tmr->lock, flags); /* setup defaults */ tmr->ppq = 96; /* 96 PPQ */ tmr->tempo = 500000; /* 120 BPM */ @@ -105,21 +108,25 @@ void snd_seq_timer_defaults(struct snd_seq_timer * tmr) tmr->preferred_resolution = seq_default_timer_resolution; tmr->skew = tmr->skew_base = SKEW_BASE; + spin_unlock_irqrestore(&tmr->lock, flags); } -void snd_seq_timer_reset(struct snd_seq_timer * tmr) +static void seq_timer_reset(struct snd_seq_timer *tmr) { - unsigned long flags; - - spin_lock_irqsave(&tmr->lock, flags); - /* reset time & songposition */ tmr->cur_time.tv_sec = 0; tmr->cur_time.tv_nsec = 0; tmr->tick.cur_tick = 0; tmr->tick.fraction = 0; +} + +void snd_seq_timer_reset(struct snd_seq_timer *tmr) +{ + unsigned long flags; + spin_lock_irqsave(&tmr->lock, flags); + seq_timer_reset(tmr); spin_unlock_irqrestore(&tmr->lock, flags); } @@ -138,8 +145,11 @@ static void snd_seq_timer_interrupt(struct snd_timer_instance *timeri, tmr = q->timer; if (tmr == NULL) return; - if (!tmr->running) + spin_lock_irqsave(&tmr->lock, flags); + if (!tmr->running) { + spin_unlock_irqrestore(&tmr->lock, flags); return; + } resolution *= ticks; if (tmr->skew != tmr->skew_base) { @@ -148,8 +158,6 @@ static void snd_seq_timer_interrupt(struct snd_timer_instance *timeri, (((resolution & 0xffff) * tmr->skew) >> 16); } - spin_lock_irqsave(&tmr->lock, flags); - /* update timer */ snd_seq_inc_time_nsec(&tmr->cur_time, resolution); @@ -296,26 +304,30 @@ int snd_seq_timer_open(struct snd_seq_queue *q) t->callback = snd_seq_timer_interrupt; t->callback_data = q; t->flags |= SNDRV_TIMER_IFLG_AUTO; + spin_lock_irq(&tmr->lock); tmr->timeri = t; + spin_unlock_irq(&tmr->lock); return 0; } int snd_seq_timer_close(struct snd_seq_queue *q) { struct snd_seq_timer *tmr; + struct snd_timer_instance *t; tmr = q->timer; if (snd_BUG_ON(!tmr)) return -EINVAL; - if (tmr->timeri) { - snd_timer_stop(tmr->timeri); - snd_timer_close(tmr->timeri); - tmr->timeri = NULL; - } + spin_lock_irq(&tmr->lock); + t = tmr->timeri; + tmr->timeri = NULL; + spin_unlock_irq(&tmr->lock); + if (t) + snd_timer_close(t); return 0; } -int snd_seq_timer_stop(struct snd_seq_timer * tmr) +static int seq_timer_stop(struct snd_seq_timer *tmr) { if (! tmr->timeri) return -EINVAL; @@ -326,6 +338,17 @@ int snd_seq_timer_stop(struct snd_seq_timer * tmr) return 0; } +int snd_seq_timer_stop(struct snd_seq_timer *tmr) +{ + unsigned long flags; + int err; + + spin_lock_irqsave(&tmr->lock, flags); + err = seq_timer_stop(tmr); + spin_unlock_irqrestore(&tmr->lock, flags); + return err; +} + static int initialize_timer(struct snd_seq_timer *tmr) { struct snd_timer *t; @@ -358,13 +381,13 @@ static int initialize_timer(struct snd_seq_timer *tmr) return 0; } -int snd_seq_timer_start(struct snd_seq_timer * tmr) +static int seq_timer_start(struct snd_seq_timer *tmr) { if (! tmr->timeri) return -EINVAL; if (tmr->running) - snd_seq_timer_stop(tmr); - snd_seq_timer_reset(tmr); + seq_timer_stop(tmr); + seq_timer_reset(tmr); if (initialize_timer(tmr) < 0) return -EINVAL; snd_timer_start(tmr->timeri, tmr->ticks); @@ -373,14 +396,25 @@ int snd_seq_timer_start(struct snd_seq_timer * tmr) return 0; } -int snd_seq_timer_continue(struct snd_seq_timer * tmr) +int snd_seq_timer_start(struct snd_seq_timer *tmr) +{ + unsigned long flags; + int err; + + spin_lock_irqsave(&tmr->lock, flags); + err = seq_timer_start(tmr); + spin_unlock_irqrestore(&tmr->lock, flags); + return err; +} + +static int seq_timer_continue(struct snd_seq_timer *tmr) { if (! tmr->timeri) return -EINVAL; if (tmr->running) return -EBUSY; if (! tmr->initialized) { - snd_seq_timer_reset(tmr); + seq_timer_reset(tmr); if (initialize_timer(tmr) < 0) return -EINVAL; } @@ -390,11 +424,24 @@ int snd_seq_timer_continue(struct snd_seq_timer * tmr) return 0; } +int snd_seq_timer_continue(struct snd_seq_timer *tmr) +{ + unsigned long flags; + int err; + + spin_lock_irqsave(&tmr->lock, flags); + err = seq_timer_continue(tmr); + spin_unlock_irqrestore(&tmr->lock, flags); + return err; +} + /* return current 'real' time. use timeofday() to get better granularity. */ snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr) { snd_seq_real_time_t cur_time; + unsigned long flags; + spin_lock_irqsave(&tmr->lock, flags); cur_time = tmr->cur_time; if (tmr->running) { struct timeval tm; @@ -410,7 +457,7 @@ snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr) } snd_seq_sanity_real_time(&cur_time); } - + spin_unlock_irqrestore(&tmr->lock, flags); return cur_time; }