linux/sound/core
Takashi Iwai 9f8a7658bc ALSA: timer: Fix zero-division by continue of uninitialized instance
When a user timer instance is continued without the explicit start
beforehand, the system gets eventually zero-division error like:

  divide error: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN
  CPU: 1 PID: 27320 Comm: syz-executor Not tainted 4.8.0-rc3-next-20160825+ #8
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
   task: ffff88003c9b2280 task.stack: ffff880027280000
   RIP: 0010:[<ffffffff858e1a6c>]  [<     inline     >] ktime_divns include/linux/ktime.h:195
   RIP: 0010:[<ffffffff858e1a6c>]  [<ffffffff858e1a6c>] snd_hrtimer_callback+0x1bc/0x3c0 sound/core/hrtimer.c:62
  Call Trace:
   <IRQ>
   [<     inline     >] __run_hrtimer kernel/time/hrtimer.c:1238
   [<ffffffff81504335>] __hrtimer_run_queues+0x325/0xe70 kernel/time/hrtimer.c:1302
   [<ffffffff81506ceb>] hrtimer_interrupt+0x18b/0x420 kernel/time/hrtimer.c:1336
   [<ffffffff8126d8df>] local_apic_timer_interrupt+0x6f/0xe0 arch/x86/kernel/apic/apic.c:933
   [<ffffffff86e13056>] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:957
   [<ffffffff86e1210c>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:487
   <EOI>
   .....

Although a similar issue was spotted and a fix patch was merged in
commit [6b760bb2c6: ALSA: timer: fix division by zero after
SNDRV_TIMER_IOCTL_CONTINUE], it seems covering only a part of
iceberg.

In this patch, we fix the issue a bit more drastically.  Basically the
continue of an uninitialized timer is supposed to be a fresh start, so
we do it for user timers.  For the direct snd_timer_continue() call,
there is no way to pass the initial tick value, so we kick out for the
uninitialized case.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-09-08 10:45:05 +02:00
..
oss ALSA: pcm: Fix potential deadlock in OSS emulation 2016-02-01 12:23:29 +01:00
seq ALSA: seq_timer: use monotonic times internally 2016-06-17 22:56:13 +02:00
compress_offload.c ALSA: compress: Add function to indicate the stream has gone bad 2016-06-13 16:45:37 +01:00
control_compat.c ALSA: ctl: change return value in compatibility layer so that it's the same value in core implementation 2016-03-17 14:11:36 +01:00
control.c Merge branch 'for-next' into for-linus 2016-07-25 17:01:14 +02:00
ctljack.c ALSA: jack: Fix endless loop at unique index detection 2015-06-26 06:59:57 +02:00
device.c Merge branch 'topic/hda-unbind' into for-next 2015-03-16 14:48:20 +01:00
hrtimer.c ALSA: hrtimer: Handle start/stop more properly 2016-04-26 09:34:40 +02:00
hwdep_compat.c
hwdep.c ALSA: replace CONFIG_PROC_FS with CONFIG_SND_PROC_FS 2015-05-27 21:25:19 +02:00
info_oss.c ALSA: core: Clean up OSS proc file management 2015-04-24 17:31:08 +02:00
info.c ALSA: info: Drop kerneldoc comment from snd_info_create_entry() 2015-05-18 09:45:11 +02:00
init.c ALSA: hda_intel: add card number to irq description 2016-01-12 21:05:16 +01:00
isadma.c ALSA: core: Use standard printk helpers 2014-02-14 08:14:15 +01:00
jack.c ALSA: jack: Allow building the jack layer without input device 2016-02-23 09:03:07 +01:00
Kconfig ALSA: timer: remove legacy rtctimer 2016-04-25 10:41:46 +02:00
Makefile ALSA: timer: remove legacy rtctimer 2016-04-25 10:41:46 +02:00
memalloc.c genalloc: rename of_get_named_gen_pool() to of_gen_pool_get() 2015-06-30 19:45:01 -07:00
memory.c ALSA: Include linux/uaccess.h and linux/bitopts.h instead of asm/* 2015-01-28 17:25:07 +01:00
misc.c ALSA: Allow pass NULL dev for snd_pci_quirk_lookup() 2014-10-08 12:08:38 +02:00
pcm_compat.c ALSA: pcm: Fix ioctls for X32 ABI 2016-02-28 17:44:35 +01:00
pcm_dmaengine.c ASoC: dmaengine_pcm: Add support for packed transfers 2016-04-27 17:34:11 +01:00
pcm_drm_eld.c ALSA: pcm: add DRM ELD helper 2015-05-22 16:01:44 +02:00
pcm_iec958.c ALSA: pcm: Allow 32 bit sample format in IEC958 channel status helper 2016-04-06 14:33:38 -07:00
pcm_lib.c ALSA: pcm: Bail out when chmap is already present 2016-05-10 17:05:16 +02:00
pcm_memory.c ALSA: Include linux/io.h instead of asm/io.h 2015-01-28 16:49:33 +01:00
pcm_misc.c ALSA: pcm: Add snd_pcm_rate_range_to_bits() 2016-02-05 18:49:00 +00:00
pcm_native.c ALSA: pcm: Fix poll error return codes 2016-05-09 17:34:49 +02:00
pcm_timer.c ALSA: pcm: Use standard printk helpers 2014-02-14 08:14:15 +01:00
pcm_trace.h ALSA: pcm: Replace PCM hwptr tracking with tracepoints 2014-11-04 14:09:14 +01:00
pcm.c ALSA: pcm: Free chmap at PCM free callback, too 2016-07-08 09:15:44 +02:00
rawmidi_compat.c ALSA: rawmidi: Fix ioctls X32 ABI 2016-02-28 17:44:51 +01:00
rawmidi.c ALSA: rawmidi: Fix race at copying & updating the position 2016-02-03 14:51:42 +01:00
sgbuf.c ALSA: core: Deletion of unnecessary checks before two function calls 2014-11-21 20:06:57 +01:00
sound_oss.c ALSA: replace CONFIG_PROC_FS with CONFIG_SND_PROC_FS 2015-05-27 21:25:19 +02:00
sound.c ALSA: replace CONFIG_PROC_FS with CONFIG_SND_PROC_FS 2015-05-27 21:25:19 +02:00
timer_compat.c ALSA: timer: fix gparams ioctl compatibility for different architectures 2016-03-23 08:06:16 +01:00
timer.c ALSA: timer: Fix zero-division by continue of uninitialized instance 2016-09-08 10:45:05 +02:00
vmaster.c ALSA: core: Use standard printk helpers 2014-02-14 08:14:15 +01:00