iMX/i2som-imx-linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ALSA: timer: Reject user params with too small ticks

Browse Source 
commit 71321eb3f2 upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai
2017-02-28 14:49:07 +01:00
committed by Greg Kroah-Hartman
parent 51ce9867c2
commit 5ac9276dd1
1 changed files with 15 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
sound/core/timer.c
View File

@ -1702,9 +1702,21 @@ static int snd_timer_user_params(struct file *file,
return -EBADFD;
if (copy_from_user(&params, _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)) {