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authorTakashi Iwai <tiwai@suse.de>2016-01-13 17:48:01 +0100
committerZiyan <jaraidaniel@gmail.com>2016-10-29 01:34:09 +0200
commitae0cd84a5532660bad66fd56bae4fded42281c80 (patch)
treea2e3960bc479af732208ae2eefb17d9d956a2f72 /sound
parent1056b8cb1418680fc3691266b491524101ce57de (diff)
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ALSA: timer: Fix race among timer ioctls
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. Change-Id: Iaa21b00f62e02cc58e346a29846e0fce6536e860 Reported-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/timer.c32
1 files changed, 19 insertions, 13 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c
index e8a12f3..eb2da96 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -72,7 +72,7 @@ struct snd_timer_user {
struct timespec tstamp; /* trigger tstamp */
wait_queue_head_t qchange_sleep;
struct fasync_struct *fasync;
- struct mutex tread_sem;
+ struct mutex ioctl_lock;
};
/* list of timers */
@@ -1252,7 +1252,7 @@ static int snd_timer_user_open(struct inode *inode, struct file *file)
return -ENOMEM;
spin_lock_init(&tu->qlock);
init_waitqueue_head(&tu->qchange_sleep);
- mutex_init(&tu->tread_sem);
+ mutex_init(&tu->ioctl_lock);
tu->ticks = 1;
tu->queue_size = 128;
tu->queue = kmalloc(tu->queue_size * sizeof(struct snd_timer_read),
@@ -1272,8 +1272,10 @@ static int snd_timer_user_release(struct inode *inode, struct file *file)
if (file->private_data) {
tu = file->private_data;
file->private_data = NULL;
+ mutex_lock(&tu->ioctl_lock);
if (tu->timeri)
snd_timer_close(tu->timeri);
+ mutex_unlock(&tu->ioctl_lock);
kfree(tu->queue);
kfree(tu->tqueue);
kfree(tu);
@@ -1511,7 +1513,6 @@ static int snd_timer_user_tselect(struct file *file,
int err = 0;
tu = file->private_data;
- mutex_lock(&tu->tread_sem);
if (tu->timeri) {
snd_timer_close(tu->timeri);
tu->timeri = NULL;
@@ -1555,7 +1556,6 @@ static int snd_timer_user_tselect(struct file *file,
}
__err:
- mutex_unlock(&tu->tread_sem);
return err;
}
@@ -1768,7 +1768,7 @@ enum {
SNDRV_TIMER_IOCTL_PAUSE_OLD = _IO('T', 0x23),
};
-static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
+static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct snd_timer_user *tu;
@@ -1785,17 +1785,11 @@ static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
{
int xarg;
- mutex_lock(&tu->tread_sem);
- if (tu->timeri) { /* too late */
- mutex_unlock(&tu->tread_sem);
+ if (tu->timeri) /* too late */
return -EBUSY;
- }
- if (get_user(xarg, p)) {
- mutex_unlock(&tu->tread_sem);
+ if (get_user(xarg, p))
return -EFAULT;
- }
tu->tread = xarg ? 1 : 0;
- mutex_unlock(&tu->tread_sem);
return 0;
}
case SNDRV_TIMER_IOCTL_GINFO:
@@ -1828,6 +1822,18 @@ static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
return -ENOTTY;
}
+static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct snd_timer_user *tu = file->private_data;
+ long ret;
+
+ mutex_lock(&tu->ioctl_lock);
+ ret = __snd_timer_user_ioctl(file, cmd, arg);
+ mutex_unlock(&tu->ioctl_lock);
+ return ret;
+}
+
static int snd_timer_user_fasync(int fd, struct file * file, int on)
{
struct snd_timer_user *tu;