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| author | Takashi Iwai <tiwai@suse.de> | 2017-02-28 14:49:07 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2017-02-28 15:06:01 +0100 |
| commit | 71321eb3f2d0df4e6c327e0b936eec4458a12054 (patch) | |
| tree | 71fcacadc0b01afc9f386840d8089322631c2332 | |
| parent | 126cfa2f5e15ae2ca7f70be71b07e6cd8d2b44d1 (diff) | |
| download | linux-71321eb3f2d0df4e6c327e0b936eec4458a12054.tar.bz2 | |
ALSA: timer: Reject user params with too small ticks
When a user sets a too small ticks with a fine-grained timer like
hrtimer, the kernel tries to fire up the timer irq too frequently.
This may lead to the condensed locks, eventually the kernel spinlock
lockup with warnings.
For avoiding such a situation, we define a lower limit of the
resolution, namely 1ms. When the user passes a too small tick value
that results in less than that, the kernel returns -EINVAL now.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | sound/core/timer.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c index fc144f43faa6..ad153149b231 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -1702,9 +1702,21 @@ static int snd_timer_user_params(struct file *file, return -EBADFD; if (copy_from_user(¶ms, _params, sizeof(params))) return -EFAULT; - if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE) && params.ticks < 1) { - err = -EINVAL; - goto _end; + if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE)) { + u64 resolution; + + if (params.ticks < 1) { + err = -EINVAL; + goto _end; + } + + /* Don't allow resolution less than 1ms */ + resolution = snd_timer_resolution(tu->timeri); + resolution *= params.ticks; + if (resolution < 1000000) { + err = -EINVAL; + goto _end; + } } if (params.queue_size > 0 && (params.queue_size < 32 || params.queue_size > 1024)) { |