Revision 7e1d90f60a0d501c8503e636942ca704a454d910 authored by Daniel Mentz on 14 August 2017, 21:46:01 UTC, committed by Takashi Iwai on 15 August 2017, 06:02:35 UTC
commit 4842e98f26dd80be3623c4714a244ba52ea096a8 ("ALSA: seq: Fix race at creating a queue") attempted to fix a race reported by syzkaller. That fix has been described as follows: " When a sequencer queue is created in snd_seq_queue_alloc(),it adds the new queue element to the public list before referencing it. Thus the queue might be deleted before the call of snd_seq_queue_use(), and it results in the use-after-free error, as spotted by syzkaller. The fix is to reference the queue object at the right time. " Even with that fix in place, syzkaller reported a use-after-free error. It specifically pointed to the last instruction "return q->queue" in snd_seq_queue_alloc(). The pointer q is being used after kfree() has been called on it. It turned out that there is still a small window where a race can happen. The window opens at snd_seq_ioctl_create_queue()->snd_seq_queue_alloc()->queue_list_add() and closes at snd_seq_ioctl_create_queue()->queueptr()->snd_use_lock_use(). Between these two calls, a different thread could delete the queue and possibly re-create a different queue in the same location in queue_list. This change prevents this situation by calling snd_use_lock_use() from snd_seq_queue_alloc() prior to calling queue_list_add(). It is then the caller's responsibility to call snd_use_lock_free(&q->use_lock). Fixes: 4842e98f26dd ("ALSA: seq: Fix race at creating a queue") Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Daniel Mentz <danielmentz@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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File | Mode | Size |
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accel | ||
adc | ||
amplifiers | ||
buffer | ||
chemical | ||
common | ||
counter | ||
dac | ||
dummy | ||
frequency | ||
gyro | ||
health | ||
humidity | ||
imu | ||
light | ||
magnetometer | ||
multiplexer | ||
orientation | ||
potentiometer | ||
potentiostat | ||
pressure | ||
proximity | ||
temperature | ||
trigger | ||
Kconfig | -rw-r--r-- | 2.8 KB |
Makefile | -rw-r--r-- | 953 bytes |
iio_core.h | -rw-r--r-- | 2.5 KB |
iio_core_trigger.h | -rw-r--r-- | 1.3 KB |
industrialio-buffer.c | -rw-r--r-- | 36.2 KB |
industrialio-configfs.c | -rw-r--r-- | 1.2 KB |
industrialio-core.c | -rw-r--r-- | 46.0 KB |
industrialio-event.c | -rw-r--r-- | 14.3 KB |
industrialio-sw-device.c | -rw-r--r-- | 4.2 KB |
industrialio-sw-trigger.c | -rw-r--r-- | 4.2 KB |
industrialio-trigger.c | -rw-r--r-- | 19.6 KB |
industrialio-triggered-event.c | -rw-r--r-- | 2.3 KB |
inkern.c | -rw-r--r-- | 20.8 KB |
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