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authorTakashi Iwai <tiwai@suse.de>2019-11-06 16:42:57 +0100
committerTakashi Iwai <tiwai@suse.de>2019-11-06 17:57:52 +0100
commitfdea53fe5de532969a332d6e5e727f2ad8bf084d (patch)
treeedb9a592f464c587aa6ac1afb50fd194f3479459 /sound/core/timer.c
parentb65f131b8f47b399a0635f028af3888f8c741ae1 (diff)
ALSA: timer: Limit max amount of slave instances
The fuzzer tries to open the timer instances as much as possible, and this may cause a system hiccup easily. We've already introduced the cap for the max number of available instances for the h/w timers, and we should put such a limit also to the slave timers, too. This patch introduces the limit to the multiple opened slave timers. The upper limit is hard-coded to 1000 for now, which should suffice for any practical usages up to now. Link: https://lore.kernel.org/r/20191106154257.5853-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core/timer.c')
-rw-r--r--sound/core/timer.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 5c9fbf3f4340..219249627cc3 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -74,6 +74,9 @@ static LIST_HEAD(snd_timer_slave_list);
/* lock for slave active lists */
static DEFINE_SPINLOCK(slave_active_lock);
+#define MAX_SLAVE_INSTANCES 1000
+static int num_slaves;
+
static DEFINE_MUTEX(register_mutex);
static int snd_timer_free(struct snd_timer *timer);
@@ -250,6 +253,10 @@ int snd_timer_open(struct snd_timer_instance **ti,
err = -EINVAL;
goto unlock;
}
+ if (num_slaves >= MAX_SLAVE_INSTANCES) {
+ err = -EBUSY;
+ goto unlock;
+ }
timeri = snd_timer_instance_new(owner, NULL);
if (!timeri) {
err = -ENOMEM;
@@ -259,6 +266,7 @@ int snd_timer_open(struct snd_timer_instance **ti,
timeri->slave_id = tid->device;
timeri->flags |= SNDRV_TIMER_IFLG_SLAVE;
list_add_tail(&timeri->open_list, &snd_timer_slave_list);
+ num_slaves++;
err = snd_timer_check_slave(timeri);
if (err < 0) {
snd_timer_close_locked(timeri);
@@ -350,6 +358,8 @@ static int snd_timer_close_locked(struct snd_timer_instance *timeri)
}
list_del(&timeri->open_list);
+ if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
+ num_slaves--;
/* force to stop the timer */
snd_timer_stop(timeri);