In loopback_open() and loopback_close(), we assign and release the
substream object to the corresponding cable in a racy way. It's
neither locked nor done in the right position. The open callback
assigns the substream before its preparation finishes, hence the other
side of the cable may pick it up, which may lead to the invalid memory
access.
This patch addresses these: move the assignment to the end of the open
callback, and wrap with cable->lock for avoiding concurrent accesses.
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The aloop driver tries to stop the pending timer via timer_del() in
the trigger callback and in the close callback. The former is
correct, as it's an atomic operation, while the latter expects that
the timer gets really removed and proceeds the resource releases after
that. But timer_del() doesn't synchronize, hence the running timer
may still access the released resources.
A similar situation can be also seen in the prepare callback after
trigger(STOP) where the prepare tries to re-initialize the things
while a timer is still running.
The problems like the above are seen indirectly in some syzkaller
reports (although it's not 100% clear whether this is the only cause,
as the race condition is quite narrow and not always easy to
trigger).
For addressing these issues, this patch adds the explicit alls of
timer_del_sync() in some places, so that the pending timer is properly
killed / synced.
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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: b1c73fc8e6 ("ALSA: snd-aloop: Fix hw_params restrictions and checking")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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: b1c73fc8e6 ("ALSA: snd-aloop: Fix hw_params restrictions and checking")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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: 597603d615 ("ALSA: introduce the snd-aloop module for the PCM loopback")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
snd_pcm_ops are not supposed to change at runtime. All functions
working with snd_pcm_ops provided by <sound/pcm.h> work with
const snd_pcm_ops. So mark the non-const structs as const.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Make these const as they are only used in a copy operation.
Done using Coccinelle.
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Commit 0998d06310 (device-core: Ensure drvdata = NULL when no
driver is bound) removes the need to set driver data field to
NULL.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add a function to handle conversion from snd_pcm_format_t
to bitwise with proper typing.
Change such conversions to use this function and silence sparse
warnings.
Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
snd-aloop driver has no proper PM implementation, thus the PM resume
may trigger Oops due to leftover timer instance. This patch adds the
missing suspend/resume implementation.
Reported-and-tested-by: El boulangero <elboulangero@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
CONFIG_HOTPLUG is going away as an option. As result the __dev*
markings will be going away.
Remove use of __devinit, __devexit_p, __devinitdata, __devinitconst,
and __devexit.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
There are small races opened in the check of running bit and the timer
lock. Instead of adding yet more flag, just protect the whole racy
codes with the existing cable->lock. As a bonus, we can get rid of
timer_lock now.
Reported-and-tested-by: Omair Mohammed Abdullah <omair.m.abdullah@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
When the loopback timer handler is running, calling del_timer() (for STOP
trigger) will not wait for the handler to complete before deactivating the
timer. The timer gets rescheduled in the handler as usual. Then a subsequent
START trigger will try to start the timer using add_timer() with a timer pending
leading to a kernel panic.
Serialize the calls to add_timer() and del_timer() using a spin lock to avoid
this.
Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
When CONFIG_PM is set but CONFIG_PM_SLEEP is unset,
SIMPLE_DEV_PM_OPS() ignores the given functions, and this leads to
compile warnings.
For avoiding this, simply check CONFIG_PM_SLEEP instead of CONFIG_PM.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Maintain both streams (playback, capture) synchronized. Previous code
didn't take in account the small byte count drifts caused by the irq
position rounding.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
module_param(bool) used to counter-intuitively take an int. In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.
It's time to remove the int/unsigned int option. For this version
it'll simply give a warning, but it'll break next kernel version.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The implicit presence of module.h lured several users into
incorrectly thinking that they only needed/used modparam.h
but once we clean up the module.h presence, these will show
up as build failures, so fix 'em now.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
snd-aloop driver is virtual and has no need for allocating contiguous
pages. It'll be more system-friendly to use vmalloc buffers.
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
loopback_pos_update() can be called in the timer callback, thus the lock
held should be irq-safe. Otherwise you'll get AB/BA deadlock together
with substream->self_group.lock.
Reported-and-tested-by: Knut Petersen <Knut_Petersen@t-online.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
On SMP machines, the cable->running update must be atomic, otherwise
stream is not started correctly sometimes.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
In some circumstances (the rate shift value was changed), the irq_pos
value may be higher than the fraction value in the timer start function.
Check for it.
Also, to avoid value overflow, decrease maximum period size.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This patch fixes the hw_params restrictions when first (or playback) stream
sets the final hardware parameters. Also, fix the hw_params checking
in the trigger callback.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
The snd-aloop module allows redirecting of the PCM playback in the
kernel back to the user space using the standard ALSA PCM capture API.
The module also allows time synchronization with another timing source
and notifications of playback stream parameter changes.
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Takashi Iwai
Kees Cook
Arvind Yadav
Bhumika Goyal
Wolfram Sang
Sachin Kamat
Eldad Zack
Bill Pemberton
Omair Mohammed Abdullah
Jaroslav Kysela
Rusty Russell
Paul Gortmaker