linux.git/sound/core/timer.c, branch v4.14.229

ALSA: timer: Limit max amount of slave instances

2019-12-31T11:37:23+00:00

[ Upstream commit fdea53fe5de532969a332d6e5e727f2ad8bf084d ]

The fuzzer tries to open the timer instances as much as possible, and
this may cause a system hiccup easily.  We've already introduced the
cap for the max number of available instances for the h/w timers, and
we should put such a limit also to the slave timers, too.

This patch introduces the limit to the multiple opened slave timers.
The upper limit is hard-coded to 1000 for now, which should suffice
for any practical usages up to now.

Link: https://lore.kernel.org/r/20191106154257.5853-1-tiwai@suse.de
Signed-off-by: Takashi Iwai 
Signed-off-by: Sasha Levin

ALSA: timer: Fix incorrectly assigned timer instance

2019-11-12T18:17:57+00:00

commit e7af6307a8a54f0b873960b32b6a644f2d0fbd97 upstream.

The clean up commit 41672c0c24a6 ("ALSA: timer: Simplify error path in
snd_timer_open()") unified the error handling code paths with the
standard goto, but it introduced a subtle bug: the timer instance is
stored in snd_timer_open() incorrectly even if it returns an error.
This may eventually lead to UAF, as spotted by fuzzer.

The culprit is the snd_timer_open() code checks the
SNDRV_TIMER_IFLG_EXCLUSIVE flag with the common variable timeri.
This variable is supposed to be the newly created instance, but we
(ab-)used it for a temporary check before the actual creation of a
timer instance.  After that point, there is another check for the max
number of instances, and it bails out if over the threshold.  Before
the refactoring above, it worked fine because the code returned
directly from that point.  After the refactoring, however, it jumps to
the unified error path that stores the timeri variable in return --
even if it returns an error.  Unfortunately this stored value is kept
in the caller side (snd_timer_user_tselect()) in tu->timeri.  This
causes inconsistency later, as if the timer was successfully
assigned.

In this patch, we fix it by not re-using timeri variable but a
temporary variable for testing the exclusive connection, so timeri
remains NULL at that point.

Fixes: 41672c0c24a6 ("ALSA: timer: Simplify error path in snd_timer_open()")
Reported-and-tested-by: Tristan Madani 
Cc: 
Link: https://lore.kernel.org/r/20191106165547.23518-1-tiwai@suse.de
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: timer: Fix mutex deadlock at releasing card

2019-11-06T11:43:41+00:00

[ Upstream commit a39331867335d4a94b6165e306265c9e24aca073 ]

When a card is disconnected while in use, the system waits until all
opened files are closed then releases the card.  This is done via
put_device() of the card device in each device release code.

The recently reported mutex deadlock bug happens in this code path;
snd_timer_close() for the timer device deals with the global
register_mutex and it calls put_device() there.  When this timer
device is the last one, the card gets freed and it eventually calls
snd_timer_free(), which has again the protection with the global
register_mutex -- boom.

Basically put_device() call itself is race-free, so a relative simple
workaround is to move this put_device() call out of the mutex.  For
achieving that, in this patch, snd_timer_close_locked() got a new
argument to store the card device pointer in return, and each caller
invokes put_device() with the returned object after the mutex unlock.

Reported-and-tested-by: Kirill A. Shutemov 
Cc: 
Signed-off-by: Takashi Iwai 
Signed-off-by: Sasha Levin

ALSA: timer: Simplify error path in snd_timer_open()

2019-11-06T11:43:40+00:00

[ Upstream commit 41672c0c24a62699d20aab53b98d843b16483053 ]

Just a minor refactoring to use the standard goto for error paths in
snd_timer_open() instead of open code.  The first mutex_lock() is
moved to the beginning of the function to make the code clearer.

Signed-off-by: Takashi Iwai 
Signed-off-by: Sasha Levin

ALSA: timer: Fix UBSAN warning at SNDRV_TIMER_IOCTL_NEXT_DEVICE ioctl

2018-07-03T09:25:04+00:00

commit b41f794f284966fd6ec634111e3b40d241389f96 upstream.

The kernel may spew a WARNING about UBSAN undefined behavior at
handling ALSA timer ioctl SNDRV_TIMER_IOCTL_NEXT_DEVICE:

UBSAN: Undefined behaviour in sound/core/timer.c:1524:19
signed integer overflow:
2147483647 + 1 cannot be represented in type 'int'
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x122/0x1c8 lib/dump_stack.c:113
 ubsan_epilogue+0x12/0x86 lib/ubsan.c:159
 handle_overflow+0x1c2/0x21f lib/ubsan.c:190
 __ubsan_handle_add_overflow+0x2a/0x31 lib/ubsan.c:198
 snd_timer_user_next_device sound/core/timer.c:1524 [inline]
 __snd_timer_user_ioctl+0x204d/0x2520 sound/core/timer.c:1939
 snd_timer_user_ioctl+0x67/0x95 sound/core/timer.c:1994
 ....

It happens only when a value with INT_MAX is passed, as we're
incrementing it unconditionally.  So the fix is trivial, check the
value with INT_MAX.  Although the bug itself is fairly harmless, it's
better to fix it so that fuzzers won't hit this again later.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200213
Reported-and-tested-by: Team OWL337 
Cc: 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: timer: Fix pause event notification

2018-05-30T05:51:47+00:00

commit 3ae180972564846e6d794e3615e1ab0a1e6c4ef9 upstream.

Commit f65e0d299807 ("ALSA: timer: Call notifier in the same spinlock")
combined the start/continue and stop/pause functions, and in doing so
changed the event code for the pause case to SNDRV_TIMER_EVENT_CONTINUE.
Change it back to SNDRV_TIMER_EVENT_PAUSE.

Fixes: f65e0d299807 ("ALSA: timer: Call notifier in the same spinlock")
Signed-off-by: Ben Hutchings 
Cc: stable@vger.kernel.org
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: timer: Limit max instances per timer

2017-11-06T09:41:24+00:00

Currently we allow unlimited number of timer instances, and it may
bring the system hogging way too much CPU when too many timer
instances are opened and processed concurrently.  This may end up with
a soft-lockup report as triggered by syzkaller, especially when
hrtimer backend is deployed.

Since such insane number of instances aren't demanded by the normal
use case of ALSA sequencer and it merely  opens a risk only for abuse,
this patch introduces the upper limit for the number of instances per
timer backend.  As default, it's set to 1000, but for the fine-grained
timer like hrtimer, it's set to 100.

Reported-by: syzbot
Tested-by: Jérôme Glisse 
Cc: 
Signed-off-by: Takashi Iwai

ALSA: timer: Use common error handling code in alsa_timer_init()

2017-08-23T08:39:09+00:00

Add a jump target so that a bit of exception handling can be better reused
at the end of this function.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
Signed-off-by: Takashi Iwai

ALSA: timer: Adjust a condition check in snd_timer_resolution()

2017-08-23T08:37:15+00:00

The script "checkpatch.pl" pointed information out like the following.

ERROR: do not use assignment in if condition

Thus fix the affected source code place.

Signed-off-by: Markus Elfring 
Signed-off-by: Takashi Iwai

Merge tag 'sound-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound

2017-07-06T17:56:51+00:00

Pull sound updates from Takashi Iwai:
 "This development cycle resulted in a fair amount of changes in both
  core and driver sides. The most significant change in ALSA core is
  about PCM. Also the support of of-graph card and the new DAPM widget
  for DSP are noteworthy changes in ASoC core. And there're lots of
  small changes splat over the tree, as you can see in diffstat.

  Below are a few highlights:

  ALSA core:
   - Removal of set_fs() hackery from PCM core stuff, and the code
     reorganization / optimization thereafter
   - Improved support of PCM ack ops, and a new ABI for improved
     control/status mmap handling
   - Lots of constifications in various codes

  ASoC core:
   - The support of of-graph card, which may work as a better generic
     device for a replacement of simple-card
   - New widget types intended mainly for use with DSPs

  ASoC drivers:
   - New drivers for Allwinner V3s SoCs
   - Ensonic ES8316 codec support
   - More Intel SKL and KBL works
   - More device support for Intel SST Atom (mostly for cheap tablets
     and 2-in-1 devices)
   - Support for Rockchip PDM controllers
   - Support for STM32 I2S and S/PDIF controllers
   - Support for ZTE AUD96P22 codecs

  HD-audio:
   - Support of new Realtek codecs (ALC215/ALC285/ALC289), more quirks
     for HP and Dell machines
   - A few more fixes for i915 component binding"

* tag 'sound-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (418 commits)
  ALSA: hda - Fix unbalance of i915 module refcount
  ASoC: Intel: Skylake: Remove driver debugfs exit
  ASoC: Intel: Skylake: explicitly add the headers sst-dsp.h
  ALSA: hda/realtek - Remove GPIO_MASK
  ALSA: hda/realtek - Fix typo of pincfg for Dell quirk
  ALSA: pcm: add a documentation for tracepoints
  ALSA: atmel: ac97c: fix error return code in atmel_ac97c_probe()
  ALSA: x86: fix error return code in hdmi_lpe_audio_probe()
  ASoC: Intel: Skylake: Add support to read firmware registers
  ASoC: Intel: Skylake: Add sram address to sst_addr structure
  ASoC: Intel: Skylake: Debugfs facility to dump module config
  ASoC: Intel: Skylake: Add debugfs support
  ASoC: fix semicolon.cocci warnings
  ASoC: rt5645: Add quirk override by module option
  ASoC: rsnd: make arrays path and cmd_case static const
  ASoC: audio-graph-card: add widgets and routing for external amplifier support
  ASoC: audio-graph-card: update bindings for amplifier support
  ASoC: rt5665: calibration should be done before jack detection
  ASoC: rsnd: constify dev_pm_ops structures.
  ASoC: nau8825: change crosstalk-bypass property to bool type
  ...