From: Lars-Peter Clausen Date: Wed, 18 Jun 2014 11:32:34 +0000 (+0200) Subject: ALSA: control: Handle numid overflow X-Git-Tag: firefly_0821_release~176^2~3158^2~68^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ac902c112d90a89e59916f751c2745f4dbdbb4bd;p=firefly-linux-kernel-4.4.55.git ALSA: control: Handle numid overflow Each control gets automatically assigned its numids when the control is created. The allocation is done by incrementing the numid by the amount of allocated numids per allocation. This means that excessive creation and destruction of controls (e.g. via SNDRV_CTL_IOCTL_ELEM_ADD/REMOVE) can cause the id to eventually overflow. Currently when this happens for the control that caused the overflow kctl->id.numid + kctl->count will also over flow causing it to be smaller than kctl->id.numid. Most of the code assumes that this is something that can not happen, so we need to make sure that it won't happen Signed-off-by: Lars-Peter Clausen Acked-by: Jaroslav Kysela Cc: Signed-off-by: Takashi Iwai --- diff --git a/sound/core/control.c b/sound/core/control.c index 5c49f976fc7b..8d6e4bae7407 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -288,6 +288,10 @@ static bool snd_ctl_remove_numid_conflict(struct snd_card *card, { struct snd_kcontrol *kctl; + /* Make sure that the ids assigned to the control do not wrap around */ + if (card->last_numid >= UINT_MAX - count) + card->last_numid = 0; + list_for_each_entry(kctl, &card->controls, list) { if (kctl->id.numid < card->last_numid + 1 + count && kctl->id.numid + kctl->count > card->last_numid + 1) {