linux-toradex.git/sound, branch v4.15

ALSA: seq: Make ioctls race-free

2018-01-11T13:37:51+00:00

The ALSA sequencer ioctls have no protection against racy calls while
the concurrent operations may lead to interfere with each other.  As
reported recently, for example, the concurrent calls of setting client
pool with a combination of write calls may lead to either the
unkillable dead-lock or UAF.

As a slightly big hammer solution, this patch introduces the mutex to
make each ioctl exclusive.  Although this may reduce performance via
parallel ioctl calls, usually it's not demanded for sequencer usages,
hence it should be negligible.

Reported-by: Luo Quan 
Reviewed-by: Kees Cook 
Reviewed-by: Greg Kroah-Hartman 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Remove yet superfluous WARN_ON()

2018-01-10T23:01:26+00:00

muldiv32() contains a snd_BUG_ON() (which is morphed as WARN_ON() with
debug option) for checking the case of 0 / 0.  This would be helpful
if this happens only as a logical error; however, since the hw refine
is performed with any data set provided by user, the inconsistent
values that can trigger such a condition might be passed easily.
Actually, syzbot caught this by passing some zero'ed old hw_params
ioctl.

So, having snd_BUG_ON() there is simply superfluous and rather
harmful to give unnecessary confusions.  Let's get rid of it.

Reported-by: syzbot+7e6ee55011deeebce15d@syzkaller.appspotmail.com
Cc: 
Signed-off-by: Takashi Iwai

ALSA: hda - Apply the existing quirk to iMac 14,1

2018-01-10T10:11:54+00:00

iMac 14,1 requires the same quirk as iMac 12,2, using GPIO 2 and 3 for
headphone and speaker output amps.  Add the codec SSID quirk entry
(106b:0600) accordingly.

BugLink: http://lkml.kernel.org/r/CAEw6Zyteav09VGHRfD5QwsfuWv5a43r0tFBNbfcHXoNrxVz7ew@mail.gmail.com
Reported-by: Freaky 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: hda - Apply headphone noise quirk for another Dell XPS 13 variant

2018-01-10T10:07:18+00:00

There is another Dell XPS 13 variant (SSID 1028:082a) that requires
the existing fixup for reducing the headphone noise.
This patch adds the quirk entry for that.

BugLink: http://lkml.kernel.org/r/CAHXyb9ZCZJzVisuBARa+UORcjRERV8yokez=DP1_5O5isTz0ZA@mail.gmail.com
Reported-and-tested-by: Francisco G. 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Allow aborting mutex lock at OSS read/write loops

2018-01-08T15:40:26+00:00

PCM OSS read/write loops keep taking the mutex lock for the whole
read/write, and this might take very long when the exceptionally high
amount of data is given.  Also, since it invokes with mutex_lock(),
the concurrent read/write becomes unbreakable.

This patch tries to address these issues by replacing mutex_lock()
with mutex_lock_interruptible(), and also splits / re-takes the lock
at each read/write period chunk, so that it can switch the context
more finely if requested.

Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Abort properly at pending signal in OSS read/write loops

2018-01-08T14:16:52+00:00

The loops for read and write in PCM OSS emulation have no proper check
of pending signals, and they keep processing even after user tries to
break.  This results in a very long delay, often seen as RCU stall
when a huge unprocessed bytes remain queued.  The bug could be easily
triggered by syzkaller.

As a simple workaround, this patch adds the proper check of pending
signals and aborts the loop appropriately.

Reported-by: syzbot+993cb4cfcbbff3947c21@syzkaller.appspotmail.com
Cc: 
Signed-off-by: Takashi Iwai

ALSA: aloop: Fix racy hw constraints adjustment

2018-01-05T15:44:16+00:00

The aloop driver tries to update the hw constraints of the connected
target on the cable of the opened PCM substream.  This is done by
adding the extra hw constraints rules referring to the substream
runtime->hw fields, while the other substream may update the runtime
hw of another side on the fly.

This is, however, racy and may result in the inconsistent values when
both PCM streams perform the prepare concurrently.  One of the reason
is that it overwrites the other's runtime->hw field; which is not only
racy but also broken when it's called before the open of another side
finishes.  And, since the reference to runtime->hw isn't protected,
the concurrent write may give the partial value update and become
inconsistent.

This patch is an attempt to fix and clean up:
- The prepare doesn't change the runtime->hw of other side any longer,
  but only update the cable->hw that is referred commonly.
- The extra rules refer to the loopback_pcm object instead of the
  runtime->hw.  The actual hw is deduced from cable->hw.
- The extra rules take the cable_lock to protect against the race.

Fixes: b1c73fc8e697 ("ALSA: snd-aloop: Fix hw_params restrictions and checking")
Cc: 
Signed-off-by: Takashi Iwai

ALSA: aloop: Fix inconsistent format due to incomplete rule

2018-01-05T15:40:16+00:00

The extra hw constraint rule for the formats the aloop driver
introduced has a slight flaw, where it doesn't return a positive value
when the mask got changed.  It came from the fact that it's basically
a copy&paste from snd_hw_constraint_mask64().  The original code is
supposed to be a single-shot and it modifies the mask bits only once
and never after, while what we need for aloop is the dynamic hw rule
that limits the mask bits.

This difference results in the inconsistent state, as the hw_refine
doesn't apply the dependencies fully.  The worse and surprisingly
result is that it causes a crash in OSS emulation when multiple
full-duplex reads/writes are performed concurrently (I leave why it
triggers Oops to readers as a homework).

For fixing this, replace a few open-codes with the standard
snd_mask_*() macros.

Reported-by: syzbot+3902b5220e8ca27889ca@syzkaller.appspotmail.com
Fixes: b1c73fc8e697 ("ALSA: snd-aloop: Fix hw_params restrictions and checking")
Cc: 
Signed-off-by: Takashi Iwai

ALSA: aloop: Release cable upon open error path

2018-01-05T15:22:20+00:00

The aloop runtime object and its assignment in the cable are left even
when opening a substream fails.  This doesn't mean any memory leak,
but it still keeps the invalid pointer that may be referred by the
another side of the cable spontaneously, which is a potential Oops
cause.

Clean up the cable assignment and the empty cable upon the error path
properly.

Fixes: 597603d615d2 ("ALSA: introduce the snd-aloop module for the PCM loopback")
Cc: 
Signed-off-by: Takashi Iwai

ALSA: pcm: Workaround for weird PulseAudio behavior on rewind error

2018-01-05T15:07:50+00:00

The commit 9027c4639ef1 ("ALSA: pcm: Call ack() whenever appl_ptr is
updated") introduced the possible error code returned from the PCM
rewind ioctl.  Basically the change was for handling the indirect PCM
more correctly, but ironically, it caused rather a side-effect:
PulseAudio gets pissed off when receiving an error from rewind, throws
everything away and stops processing further, resulting in the
silence.

It's clearly a failure in the application side, so the best would be
to fix that bug in PA.  OTOH, PA is mostly the only user of the rewind
feature, so it's not good to slap the sole customer.

This patch tries to mitigate the situation: instead of returning an
error, now the rewind ioctl returns zero when the driver can't rewind.
It indicates that no rewind was performed, so the behavior is
consistent, at least.

Fixes: 9027c4639ef1 ("ALSA: pcm: Call ack() whenever appl_ptr is updated")
Cc: 
Signed-off-by: Takashi Iwai