From 2ba1fe7a06d3624f9a7586d672b55f08f7c670f3 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 18 Jan 2016 13:52:47 +0100 Subject: ALSA: hrtimer: Fix stall by hrtimer_cancel() hrtimer_cancel() waits for the completion from the callback, thus it must not be called inside the callback itself. This was already a problem in the past with ALSA hrtimer driver, and the early commit [fcfdebe70759: ALSA: hrtimer - Fix lock-up] tried to address it. However, the previous fix is still insufficient: it may still cause a lockup when the ALSA timer instance reprograms itself in its callback. Then it invokes the start function even in snd_timer_interrupt() that is called in hrtimer callback itself, results in a CPU stall. This is no hypothetical problem but actually triggered by syzkaller fuzzer. This patch tries to fix the issue again. Now we call hrtimer_try_to_cancel() at both start and stop functions so that it won't fall into a deadlock, yet giving some chance to cancel the queue if the functions have been called outside the callback. The proper hrtimer_cancel() is called in anyway at closing, so this should be enough. Reported-and-tested-by: Dmitry Vyukov Cc: Signed-off-by: Takashi Iwai --- sound/core/hrtimer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'sound/core') diff --git a/sound/core/hrtimer.c b/sound/core/hrtimer.c index f845ecf..656d9a9 100644 --- a/sound/core/hrtimer.c +++ b/sound/core/hrtimer.c @@ -90,7 +90,7 @@ static int snd_hrtimer_start(struct snd_timer *t) struct snd_hrtimer *stime = t->private_data; atomic_set(&stime->running, 0); - hrtimer_cancel(&stime->hrt); + hrtimer_try_to_cancel(&stime->hrt); hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution), HRTIMER_MODE_REL); atomic_set(&stime->running, 1); @@ -101,6 +101,7 @@ static int snd_hrtimer_stop(struct snd_timer *t) { struct snd_hrtimer *stime = t->private_data; atomic_set(&stime->running, 0); + hrtimer_try_to_cancel(&stime->hrt); return 0; } -- cgit v1.1 From 43c54b8c7cfe22f868a751ba8a59abf1724160b1 Mon Sep 17 00:00:00 2001 From: Nicolas Boichat Date: Mon, 18 Jan 2016 21:35:00 +0800 Subject: ALSA: pcm: Fix snd_pcm_hw_params struct copy in compat mode This reverts one hunk of commit ef44a1ec6eee ("ALSA: sound/core: use memdup_user()"), which replaced a number of kmalloc followed by memcpy with memdup calls. In this case, we are copying from a struct snd_pcm_hw_params32 to a struct snd_pcm_hw_params, but the latter is 4 bytes longer than the 32-bit version, so we need to separate kmalloc and copy calls. This actually leads to an out-of-bounds memory access later on in sound/soc/soc-pcm.c:soc_pcm_hw_params() (detected using KASan). Fixes: ef44a1ec6eee ('ALSA: sound/core: use memdup_user()') Signed-off-by: Nicolas Boichat Cc: Signed-off-by: Takashi Iwai --- sound/core/pcm_compat.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'sound/core') diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c index b48b434..9630e9f 100644 --- a/sound/core/pcm_compat.c +++ b/sound/core/pcm_compat.c @@ -255,10 +255,15 @@ static int snd_pcm_ioctl_hw_params_compat(struct snd_pcm_substream *substream, if (! (runtime = substream->runtime)) return -ENOTTY; - /* only fifo_size is different, so just copy all */ - data = memdup_user(data32, sizeof(*data32)); - if (IS_ERR(data)) - return PTR_ERR(data); + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + /* only fifo_size (RO from userspace) is different, so just copy all */ + if (copy_from_user(data, data32, sizeof(*data32))) { + err = -EFAULT; + goto error; + } if (refine) err = snd_pcm_hw_refine(substream, data); -- cgit v1.1 From 9586495dc3011a80602329094e746dbce16cb1f1 Mon Sep 17 00:00:00 2001 From: Nicolas Boichat Date: Mon, 18 Jan 2016 21:35:01 +0800 Subject: ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode This reverts one hunk of commit ef44a1ec6eee ("ALSA: sound/core: use memdup_user()"), which replaced a number of kmalloc followed by memcpy with memdup calls. In this case, we are copying from a struct snd_seq_port_info32 to a struct snd_seq_port_info, but the latter is 4 bytes longer than the 32-bit version, so we need to separate kmalloc and copy calls. Fixes: ef44a1ec6eee ('ALSA: sound/core: use memdup_user()') Signed-off-by: Nicolas Boichat Cc: Signed-off-by: Takashi Iwai --- sound/core/seq/seq_compat.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'sound/core') diff --git a/sound/core/seq/seq_compat.c b/sound/core/seq/seq_compat.c index 81f7c10..6517590 100644 --- a/sound/core/seq/seq_compat.c +++ b/sound/core/seq/seq_compat.c @@ -49,11 +49,12 @@ static int snd_seq_call_port_info_ioctl(struct snd_seq_client *client, unsigned struct snd_seq_port_info *data; mm_segment_t fs; - data = memdup_user(data32, sizeof(*data32)); - if (IS_ERR(data)) - return PTR_ERR(data); + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; - if (get_user(data->flags, &data32->flags) || + if (copy_from_user(data, data32, sizeof(*data32)) || + get_user(data->flags, &data32->flags) || get_user(data->time_queue, &data32->time_queue)) goto error; data->kernel = NULL; -- cgit v1.1 From c0bcdbdff3ff73a54161fca3cb8b6cdbd0bb8762 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 18 Jan 2016 14:12:40 +0100 Subject: ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0 When a TLV ioctl with numid zero is handled, the driver may spew a kernel warning with a stack trace at each call. The check was intended obviously only for a kernel driver, but not for a user interaction. Let's fix it. This was spotted by syzkaller fuzzer. Reported-by: Dmitry Vyukov Cc: Signed-off-by: Takashi Iwai --- sound/core/control.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'sound/core') diff --git a/sound/core/control.c b/sound/core/control.c index 196a6fe..a85d455 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -1405,6 +1405,8 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file, return -EFAULT; if (tlv.length < sizeof(unsigned int) * 2) return -EINVAL; + if (!tlv.numid) + return -EINVAL; down_read(&card->controls_rwsem); kctl = snd_ctl_find_numid(card, tlv.numid); if (kctl == NULL) { -- cgit v1.1 From 230323dac060123c340cf75997971145a42661ee Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 21 Jan 2016 17:19:31 +0100 Subject: ALSA: timer: Handle disconnection more safely Currently ALSA timer device doesn't take the disconnection into account very well; it merely unlinks the timer device at disconnection callback but does nothing else. Because of this, when an application accessing the timer device is disconnected, it may release the resource before actually closed. In most cases, it results in a warning message indicating a leftover timer instance like: ALSA: timer xxxx is busy? But basically this is an open race. This patch tries to address it. The strategy is like other ALSA devices: namely, - Manage card's refcount at each open/close - Wake up the pending tasks at disconnection - Check the shutdown flag appropriately at each possible call Note that this patch has one ugly hack to handle the wakeup of pending tasks. It'd be cleaner to introduce a new disconnect op to snd_timer_instance ops. But since it would lead to internal ABI breakage and it eventually increase my own work when backporting to stable kernels, I took a different path to implement locally in timer.c. A cleanup patch will follow at next for 4.5 kernel. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109431 Cc: # v3.15+ Signed-off-by: Takashi Iwai --- sound/core/timer.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'sound/core') diff --git a/sound/core/timer.c b/sound/core/timer.c index cb25ade..681fb05 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -65,6 +65,7 @@ struct snd_timer_user { int qtail; int qused; int queue_size; + bool disconnected; struct snd_timer_read *queue; struct snd_timer_tread *tqueue; spinlock_t qlock; @@ -290,6 +291,9 @@ int snd_timer_open(struct snd_timer_instance **ti, mutex_unlock(®ister_mutex); return -ENOMEM; } + /* take a card refcount for safe disconnection */ + if (timer->card) + get_device(&timer->card->card_dev); timeri->slave_class = tid->dev_sclass; timeri->slave_id = slave_id; if (list_empty(&timer->open_list_head) && timer->hw.open) @@ -359,6 +363,9 @@ int snd_timer_close(struct snd_timer_instance *timeri) } spin_unlock(&timer->lock); spin_unlock_irq(&slave_active_lock); + /* release a card refcount for safe disconnection */ + if (timer->card) + put_device(&timer->card->card_dev); mutex_unlock(®ister_mutex); } out: @@ -474,6 +481,8 @@ int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks) timer = timeri->timer; if (timer == NULL) return -EINVAL; + if (timer->card && timer->card->shutdown) + return -ENODEV; spin_lock_irqsave(&timer->lock, flags); timeri->ticks = timeri->cticks = ticks; timeri->pticks = 0; @@ -505,6 +514,10 @@ static int _snd_timer_stop(struct snd_timer_instance *timeri, int event) spin_lock_irqsave(&timer->lock, flags); list_del_init(&timeri->ack_list); list_del_init(&timeri->active_list); + if (timer->card && timer->card->shutdown) { + spin_unlock_irqrestore(&timer->lock, flags); + return 0; + } if ((timeri->flags & SNDRV_TIMER_IFLG_RUNNING) && !(--timer->running)) { timer->hw.stop(timer); @@ -565,6 +578,8 @@ int snd_timer_continue(struct snd_timer_instance *timeri) timer = timeri->timer; if (! timer) return -EINVAL; + if (timer->card && timer->card->shutdown) + return -ENODEV; spin_lock_irqsave(&timer->lock, flags); if (!timeri->cticks) timeri->cticks = 1; @@ -628,6 +643,9 @@ static void snd_timer_tasklet(unsigned long arg) unsigned long resolution, ticks; unsigned long flags; + if (timer->card && timer->card->shutdown) + return; + spin_lock_irqsave(&timer->lock, flags); /* now process all callbacks */ while (!list_empty(&timer->sack_list_head)) { @@ -668,6 +686,9 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left) if (timer == NULL) return; + if (timer->card && timer->card->shutdown) + return; + spin_lock_irqsave(&timer->lock, flags); /* remember the current resolution */ @@ -878,11 +899,28 @@ static int snd_timer_dev_register(struct snd_device *dev) return 0; } +/* just for reference in snd_timer_dev_disconnect() below */ +static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, + int event, struct timespec *tstamp, + unsigned long resolution); + static int snd_timer_dev_disconnect(struct snd_device *device) { struct snd_timer *timer = device->device_data; + struct snd_timer_instance *ti; + mutex_lock(®ister_mutex); list_del_init(&timer->device_list); + /* wake up pending sleepers */ + list_for_each_entry(ti, &timer->open_list_head, open_list) { + /* FIXME: better to have a ti.disconnect() op */ + if (ti->ccallback == snd_timer_user_ccallback) { + struct snd_timer_user *tu = ti->callback_data; + + tu->disconnected = true; + wake_up(&tu->qchange_sleep); + } + } mutex_unlock(®ister_mutex); return 0; } @@ -893,6 +931,8 @@ void snd_timer_notify(struct snd_timer *timer, int event, struct timespec *tstam unsigned long resolution = 0; struct snd_timer_instance *ti, *ts; + if (timer->card && timer->card->shutdown) + return; if (! (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)) return; if (snd_BUG_ON(event < SNDRV_TIMER_EVENT_MSTART || @@ -1051,6 +1091,8 @@ static void snd_timer_proc_read(struct snd_info_entry *entry, mutex_lock(®ister_mutex); list_for_each_entry(timer, &snd_timer_list, device_list) { + if (timer->card && timer->card->shutdown) + continue; switch (timer->tmr_class) { case SNDRV_TIMER_CLASS_GLOBAL: snd_iprintf(buffer, "G%i: ", timer->tmr_device); @@ -1876,6 +1918,10 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer, remove_wait_queue(&tu->qchange_sleep, &wait); + if (tu->disconnected) { + err = -ENODEV; + break; + } if (signal_pending(current)) { err = -ERESTARTSYS; break; @@ -1925,6 +1971,8 @@ static unsigned int snd_timer_user_poll(struct file *file, poll_table * wait) mask = 0; if (tu->qused) mask |= POLLIN | POLLRDNORM; + if (tu->disconnected) + mask |= POLLERR; return mask; } -- cgit v1.1 From 40ed9444cd2421cceedb35bb8d8ff913a5ae1ac3 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 21 Jan 2016 17:43:08 +0100 Subject: ALSA: timer: Introduce disconnect op to snd_timer_instance Instead of the previous ugly hack, introduce a new op, disconnect, to snd_timer_instance object for handling the wake up of pending tasks more cleanly. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109431 Signed-off-by: Takashi Iwai --- sound/core/timer.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) (limited to 'sound/core') diff --git a/sound/core/timer.c b/sound/core/timer.c index 681fb05..af1f68f 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -899,11 +899,6 @@ static int snd_timer_dev_register(struct snd_device *dev) return 0; } -/* just for reference in snd_timer_dev_disconnect() below */ -static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, - int event, struct timespec *tstamp, - unsigned long resolution); - static int snd_timer_dev_disconnect(struct snd_device *device) { struct snd_timer *timer = device->device_data; @@ -913,13 +908,8 @@ static int snd_timer_dev_disconnect(struct snd_device *device) list_del_init(&timer->device_list); /* wake up pending sleepers */ list_for_each_entry(ti, &timer->open_list_head, open_list) { - /* FIXME: better to have a ti.disconnect() op */ - if (ti->ccallback == snd_timer_user_ccallback) { - struct snd_timer_user *tu = ti->callback_data; - - tu->disconnected = true; - wake_up(&tu->qchange_sleep); - } + if (ti->disconnect) + ti->disconnect(ti); } mutex_unlock(®ister_mutex); return 0; @@ -1227,6 +1217,14 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri, wake_up(&tu->qchange_sleep); } +static void snd_timer_user_disconnect(struct snd_timer_instance *timeri) +{ + struct snd_timer_user *tu = timeri->callback_data; + + tu->disconnected = true; + wake_up(&tu->qchange_sleep); +} + static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri, unsigned long resolution, unsigned long ticks) @@ -1600,6 +1598,7 @@ static int snd_timer_user_tselect(struct file *file, ? snd_timer_user_tinterrupt : snd_timer_user_interrupt; tu->timeri->ccallback = snd_timer_user_ccallback; tu->timeri->callback_data = (void *)tu; + tu->timeri->disconnect = snd_timer_user_disconnect; } __err: -- cgit v1.1