linux-toradex.git/sound/core/seq, branch v4.4.26

ALSA: seq: oss: Don't drain at closing a client

2016-03-09T23:34:54+00:00

commit 197b958c1e76a575d77038cc98b4bebc2134279f upstream.

The OSS sequencer client tries to drain the pending events at
releasing.  Unfortunately, as spotted by syzkaller fuzzer, this may
lead to an unkillable process state when the event has been queued at
the far future.  Since the process being released can't be signaled
any longer, it remains and waits for the echo-back event in that far
future.

Back to history, the draining feature was implemented at the time we
misinterpreted POSIX definition for blocking file operation.
Actually, such a behavior is superfluous at release, and we should
just release the device as is instead of keeping it up forever.

This patch just removes the draining call that may block the release
for too long time unexpectedly.

BugLink: http://lkml.kernel.org/r/CACT4Y+Y4kD-aBGj37rf-xBw9bH3GMU6P+MYg4W1e-s-paVD2pg@mail.gmail.com
Reported-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix double port list deletion

2016-02-25T20:01:14+00:00

commit 13d5e5d4725c64ec06040d636832e78453f477b7 upstream.

The commit [7f0973e973cd: ALSA: seq: Fix lockdep warnings due to
double mutex locks] split the management of two linked lists (source
and destination) into two individual calls for avoiding the AB/BA
deadlock.  However, this may leave the possible double deletion of one
of two lists when the counterpart is being deleted concurrently.
It ends up with a list corruption, as revealed by syzkaller fuzzer.

This patch fixes it by checking the list emptiness and skipping the
deletion and the following process.

BugLink: http://lkml.kernel.org/r/CACT4Y+bay9qsrz6dQu31EcGaH9XwfW7o3oBzSQUG9fMszoh=Sg@mail.gmail.com
Fixes: 7f0973e973cd ('ALSA: seq: Fix lockdep warnings due to 'double mutex locks)
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix leak of pool buffer at concurrent writes

2016-02-25T20:01:14+00:00

commit d99a36f4728fcbcc501b78447f625bdcce15b842 upstream.

When multiple concurrent writes happen on the ALSA sequencer device
right after the open, it may try to allocate vmalloc buffer for each
write and leak some of them.  It's because the presence check and the
assignment of the buffer is done outside the spinlock for the pool.

The fix is to move the check and the assignment into the spinlock.

(The current implementation is suboptimal, as there can be multiple
 unnecessary vmallocs because the allocation is done before the check
 in the spinlock.  But the pool size is already checked beforehand, so
 this isn't a big problem; that is, the only possible path is the
 multiple writes before any pool assignment, and practically seen, the
 current coverage should be "good enough".)

The issue was triggered by syzkaller fuzzer.

BugLink: http://lkml.kernel.org/r/CACT4Y+bSzazpXNvtAr=WXaL8hptqjHwqEyFA+VN2AWEx=aurkg@mail.gmail.com
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix lockdep warnings due to double mutex locks

2016-02-17T20:30:59+00:00

commit 7f0973e973cd74aa40747c9d38844560cd184ee8 upstream.

The port subscription code uses double mutex locks for source and
destination ports, and this may become racy once when wrongly set up.
It leads to lockdep warning splat, typically triggered by fuzzer like
syzkaller, although the actual deadlock hasn't been seen, so far.

This patch simplifies the handling by reducing to two single locks, so
that no lockdep warning will be trigger any longer.

By splitting to two actions, a still-in-progress element shall be
added in one list while handling another.  For ignoring this element,
a new check is added in deliver_to_subscribers().

Along with it, the code to add/remove the subscribers list element was
cleaned up and refactored.

BugLink: http://lkml.kernel.org/r/CACT4Y+aKQXV7xkBW9hpQbzaDO7LrUvohxWh-UwMxXjDy-yBD=A@mail.gmail.com
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix race at closing in virmidi driver

2016-02-17T20:30:59+00:00

commit 2d1b5c08366acd46c35a2e9aba5d650cb5bf5c19 upstream.

The virmidi driver has an open race at closing its assigned rawmidi
device, and this may lead to use-after-free in
snd_seq_deliver_single_event().

Plug the hole by properly protecting the linked list deletion and
calling in the right order in snd_virmidi_input_close().

BugLink: http://lkml.kernel.org/r/CACT4Y+Zd66+w12fNN85-425cVQT=K23kWbhnCEcMB8s3us-Frw@mail.gmail.com
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix yet another races among ALSA timer accesses

2016-02-17T20:30:59+00:00

commit 2cdc7b636d55cbcf42e1e6c8accd85e62d3e9ae8 upstream.

ALSA sequencer may open/close and control ALSA timer instance
dynamically either via sequencer events or direct ioctls.  These are
done mostly asynchronously, and it may call still some timer action
like snd_timer_start() while another is calling snd_timer_close().
Since the instance gets removed by snd_timer_close(), it may lead to
a use-after-free.

This patch tries to address such a race by protecting each
snd_timer_*() call via the existing spinlock and also by avoiding the
access to timer during close call.

BugLink: http://lkml.kernel.org/r/CACT4Y+Z6RzW5MBr-HUdV-8zwg71WQfKTdPpYGvOeS7v4cyurNQ@mail.gmail.com
Reported-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: rawmidi: Make snd_rawmidi_transmit() race-free

2016-02-17T20:30:58+00:00

commit 06ab30034ed9c200a570ab13c017bde248ddb2a6 upstream.

A kernel WARNING in snd_rawmidi_transmit_ack() is triggered by
syzkaller fuzzer:
  WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
 [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
 [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
 [] snd_rawmidi_transmit_ack+0x275/0x400 sound/core/rawmidi.c:1136
 [] snd_virmidi_output_trigger+0x4b1/0x5a0 sound/core/seq/seq_virmidi.c:163
 [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
 [] snd_rawmidi_kernel_write1+0x549/0x780 sound/core/rawmidi.c:1223
 [] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273
 [] __vfs_write+0x113/0x480 fs/read_write.c:528
 [] vfs_write+0x167/0x4a0 fs/read_write.c:577
 [<     inline     >] SYSC_write fs/read_write.c:624
 [] SyS_write+0x111/0x220 fs/read_write.c:616
 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185

Also a similar warning is found but in another path:
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
 [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
 [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
 [] rawmidi_transmit_ack+0x24a/0x3b0 sound/core/rawmidi.c:1133
 [] snd_rawmidi_transmit_ack+0x51/0x80 sound/core/rawmidi.c:1163
 [] snd_virmidi_output_trigger+0x2b6/0x570 sound/core/seq/seq_virmidi.c:185
 [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
 [] snd_rawmidi_kernel_write1+0x4bb/0x760 sound/core/rawmidi.c:1252
 [] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1302
 [] __vfs_write+0x113/0x480 fs/read_write.c:528
 [] vfs_write+0x167/0x4a0 fs/read_write.c:577
 [<     inline     >] SYSC_write fs/read_write.c:624
 [] SyS_write+0x111/0x220 fs/read_write.c:616
 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185

In the former case, the reason is that virmidi has an open code
calling snd_rawmidi_transmit_ack() with the value calculated outside
the spinlock.   We may use snd_rawmidi_transmit() in a loop just for
consuming the input data, but even there, there is a race between
snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack().

Similarly in the latter case, it calls snd_rawmidi_transmit_peek() and
snd_rawmidi_tranmit_ack() separately without protection, so they are
racy as well.

The patch tries to address these issues by the following ways:
- Introduce the unlocked versions of snd_rawmidi_transmit_peek() and
  snd_rawmidi_transmit_ack() to be called inside the explicit lock.
- Rewrite snd_rawmidi_transmit() to be race-free (the former case).
- Make the split calls (the latter case) protected in the rawmidi spin
  lock.

BugLink: http://lkml.kernel.org/r/CACT4Y+YPq1+cYLkadwjWa5XjzF1_Vki1eHnVn-Lm0hzhSpu5PA@mail.gmail.com
BugLink: http://lkml.kernel.org/r/CACT4Y+acG4iyphdOZx47Nyq_VHGbpJQK-6xNpiqUjaZYqsXOGw@mail.gmail.com
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Degrade the error message for too many opens

2016-02-17T20:30:58+00:00

commit da10816e3d923565b470fec78a674baba794ed33 upstream.

ALSA OSS sequencer spews a kernel error message ("ALSA: seq_oss: too
many applications") when user-space tries to open more than the
limit.  This means that it can easily fill the log buffer.

Since it's merely a normal error, it's safe to suppress it via
pr_debug() instead.

Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix incorrect sanity check at snd_seq_oss_synth_cleanup()

2016-02-17T20:30:58+00:00

commit 599151336638d57b98d92338aa59c048e3a3e97d upstream.

ALSA sequencer OSS emulation code has a sanity check for currently
opened devices, but there is a thinko there, eventually it spews
warnings and skips the operation wrongly like:
  WARNING: CPU: 1 PID: 7573 at sound/core/seq/oss/seq_oss_synth.c:311

Fix this off-by-one error.

Reported-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode

2016-01-31T19:28:57+00:00

commit 9586495dc3011a80602329094e746dbce16cb1f1 upstream.

This reverts one hunk of
commit ef44a1ec6eee ("ALSA: sound/core: use memdup_user()"), which
replaced a number of kmalloc followed by memcpy with memdup calls.

In this case, we are copying from a struct snd_seq_port_info32 to a
struct snd_seq_port_info, but the latter is 4 bytes longer than the
32-bit version, so we need to separate kmalloc and copy calls.

Fixes: ef44a1ec6eee ('ALSA: sound/core: use memdup_user()')
Signed-off-by: Nicolas Boichat 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman