ALSA: timer: Fix race between read and ioctl

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commit d11662f4f7 upstream.

The read from ALSA timer device, the function snd_timer_user_tread(),
may access to an uninitialized struct snd_timer_user fields when the
read is concurrently performed while the ioctl like
snd_timer_user_tselect() is invoked.  We have already fixed the races
among ioctls via a mutex, but we seem to have forgotten the race
between read vs ioctl.

This patch simply applies (more exactly extends the already applied
range of) tu->ioctl_lock in snd_timer_user_tread() for closing the
race window.

Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Takashi Iwai 2017-06-02 15:03:38 +02:00 • committed by Greg Kroah-Hartman

parent aae14f569f

commit 66e982d8f1

1 changed files with 4 additions and 2 deletions

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sound/core/timer.c

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