From c99bd4fceec6135a31f95de4716a42e2064909bf Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Wed, 18 Jun 2014 13:32:33 +0200 Subject: [PATCH] ALSA: control: Don't access controls outside of protected regions (commit fd9f26e4eca5d08a27d12c0933fceef76ed9663d upstream) A control that is visible on the card->controls list can be freed at any time. This means we must not access any of its memory while not holding the controls_rw_lock. Otherwise we risk a use after free access. Signed-off-by: Lars-Peter Clausen Acked-by: Jaroslav Kysela Cc: Signed-off-by: Takashi Iwai [wt: fixes CVE-2014-4653] Signed-off-by: Willy Tarreau --- sound/core/control.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/sound/core/control.c b/sound/core/control.c index 8bf3a6d1ebe24..e91d79a9ec4b8 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -325,6 +325,7 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol) { struct snd_ctl_elem_id id; unsigned int idx; + unsigned int count; int err = -EINVAL; if (! kcontrol) @@ -356,8 +357,9 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol) card->controls_count += kcontrol->count; kcontrol->id.numid = card->last_numid + 1; card->last_numid += kcontrol->count; + count = kcontrol->count; up_write(&card->controls_rwsem); - for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++) + for (idx = 0; idx < count; idx++, id.index++, id.numid++) snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id); return 0; @@ -784,9 +786,9 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file, result = kctl->put(kctl, control); } if (result > 0) { + struct snd_ctl_elem_id id = control->id; up_read(&card->controls_rwsem); - snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, - &control->id); + snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id); return 0; } } -- 2.47.2