linux-stable.git/sound, branch linux-2.6.32.y

ALSA: seq: Fix race at timer setup and close

2016-03-12T13:25:48+00:00

commit 3567eb6af614dac436c4b16a8d426f9faed639b3 upstream.

ALSA sequencer code has an open race between the timer setup ioctl and
the close of the client.  This was triggered by syzkaller fuzzer, and
a use-after-free was caught there as a result.

This patch papers over it by adding a proper queue->timer_mutex lock
around the timer-related calls in the relevant code path.

Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: seq: Fix missing NULL check at remove_events ioctl

2016-03-12T13:25:47+00:00

commit 030e2c78d3a91dd0d27fef37e91950dde333eba1 upstream.

snd_seq_ioctl_remove_events() calls snd_seq_fifo_clear()
unconditionally even if there is no FIFO assigned, and this leads to
an Oops due to NULL dereference.  The fix is just to add a proper NULL
check.

Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: usb-audio: avoid freeing umidi object twice

2016-03-12T13:25:47+00:00

commit 07d86ca93db7e5cdf4743564d98292042ec21af7 upstream.

The 'umidi' object will be free'd on the error path by snd_usbmidi_free()
when tearing down the rawmidi interface. So we shouldn't try to free it
in snd_usbmidi_create() after having registered the rawmidi interface.

Found by KASAN.

Signed-off-by: Andrey Konovalov 
Acked-by: Clemens Ladisch 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
[wt: file is sound/midi/usbmidi.c in 2.6.32]
Signed-off-by: Willy Tarreau

ALSA: timer: Fix race at concurrent reads

2016-03-12T13:25:47+00:00

commit 4dff5c7b7093b19c19d3a100f8a3ad87cb7cd9e7 upstream.

snd_timer_user_read() has a potential race among parallel reads, as
qhead and qused are updated outside the critical section due to
copy_to_user() calls.  Move them into the critical section, and also
sanitize the relevant code a bit.

Signed-off-by: Takashi Iwai 
[bwh: Backported to 3.2: there's no check for tu->connected to fix up]
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: timer: Fix wrong instance passed to slave callbacks

2016-03-12T13:25:47+00:00

commit 117159f0b9d392fb433a7871426fad50317f06f7 upstream.

In snd_timer_notify1(), the wrong timer instance was passed for slave
ccallback function.  This leads to the access to the wrong data when
an incompatible master is handled (e.g. the master is the sequencer
timer and the slave is a user timer), as spotted by syzkaller fuzzer.

This patch fixes that wrong assignment.

BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.com
Reported-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: timer: Fix race among timer ioctls

2016-03-12T13:25:47+00:00

commit af368027a49a751d6ff4ee9e3f9961f35bb4fede upstream.

ALSA timer ioctls have an open race and this may lead to a
use-after-free of timer instance object.  A simplistic fix is to make
each ioctl exclusive.  We have already tread_sem for controlling the
tread, and extend this as a global mutex to be applied to each ioctl.

The downside is, of course, the worse concurrency.  But these ioctls
aren't to be parallel accessible, in anyway, so it should be fine to
serialize there.

Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: timer: Fix leftover link at closing

2016-03-12T13:25:47+00:00

commit 094fd3be87b0f102589e2d5c3fa5d06b7e20496d upstream.

In ALSA timer core, the active timer instance is managed in
active_list linked list.  Each element is added / removed dynamically
at timer start, stop and in timer interrupt.  The problem is that
snd_timer_interrupt() has a thinko and leaves the element in
active_list when it's the last opened element.  This eventually leads
to list corruption or use-after-free error.

This hasn't been revealed because we used to delete the list forcibly
in snd_timer_stop() in the past.  However, the recent fix avoids the
double-stop behavior (in commit [f784beb75ce8: ALSA: timer: Fix link
corruption due to double start or stop]), and this leak hits reality.

This patch fixes the link management in snd_timer_interrupt().  Now it
simply unlinks no matter which stream is.

BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.com
Reported-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: timer: Fix double unlink of active_list

2016-03-12T13:25:46+00:00

commit ee8413b01045c74340aa13ad5bdf905de32be736 upstream.

ALSA timer instance object has a couple of linked lists and they are
unlinked unconditionally at snd_timer_stop().  Meanwhile
snd_timer_interrupt() unlinks it, but it calls list_del() which leaves
the element list itself unchanged.  This ends up with unlinking twice,
and it was caught by syzkaller fuzzer.

The fix is to use list_del_init() variant properly there, too.

Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau

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

2016-03-12T13:25:46+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: Ben Hutchings 
Signed-off-by: Willy Tarreau

ALSA: rawmidi: Fix race at copying & updating the position

2016-03-12T13:25:46+00:00

commit 81f577542af15640cbcb6ef68baa4caa610cbbfc upstream.

The rawmidi read and write functions manage runtime stream status
such as runtime->appl_ptr and runtime->avail.  These point where to
copy the new data and how many bytes have been copied (or to be
read).  The problem is that rawmidi read/write call copy_from_user()
or copy_to_user(), and the runtime spinlock is temporarily unlocked
and relocked while copying user-space.  Since the current code
advances and updates the runtime status after the spin unlock/relock,
the copy and the update may be asynchronous, and eventually
runtime->avail might go to a negative value when many concurrent
accesses are done.  This may lead to memory corruption in the end.

For fixing this race, in this patch, the status update code is
performed in the same lock before the temporary unlock.  Also, the
spinlock is now taken more widely in snd_rawmidi_kernel_read1() for
protecting more properly during the whole operation.

BugLink: http://lkml.kernel.org/r/CACT4Y+b-dCmNf1GpgPKfDO0ih+uZCL2JV4__j-r1kdhPLSgQCQ@mail.gmail.com
Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Takashi Iwai 
Signed-off-by: Ben Hutchings 
Signed-off-by: Willy Tarreau