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ALSA: control: Don't access controls outside of protected regions

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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 <lars@metafoo.de>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Lars-Peter Clausen 2014-06-18 13:32:33 +02:00 committed by Takashi Iwai
parent 82262a4662
commit fd9f26e4ec
1 changed files with 10 additions and 5 deletions
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15
sound/core/control.c
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@ -330,6 +330,7 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
{ {
struct snd_ctl_elem_id id; struct snd_ctl_elem_id id;
unsigned int idx; unsigned int idx;
unsigned int count;
int err = -EINVAL; int err = -EINVAL;
if (! kcontrol) if (! kcontrol)
@ -358,8 +359,9 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
card->controls_count += kcontrol->count; card->controls_count += kcontrol->count;
kcontrol->id.numid = card->last_numid + 1; kcontrol->id.numid = card->last_numid + 1;
card->last_numid += kcontrol->count; card->last_numid += kcontrol->count;
count = kcontrol->count;
up_write(&card->controls_rwsem); 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); snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
return 0; return 0;
@ -388,6 +390,7 @@ int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
bool add_on_replace) bool add_on_replace)
{ {
struct snd_ctl_elem_id id; struct snd_ctl_elem_id id;
unsigned int count;
unsigned int idx; unsigned int idx;
struct snd_kcontrol *old; struct snd_kcontrol *old;
int ret; int ret;
@ -423,8 +426,9 @@ add:
card->controls_count += kcontrol->count; card->controls_count += kcontrol->count;
kcontrol->id.numid = card->last_numid + 1; kcontrol->id.numid = card->last_numid + 1;
card->last_numid += kcontrol->count; card->last_numid += kcontrol->count;
count = kcontrol->count;
up_write(&card->controls_rwsem); 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); snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
return 0; return 0;
@ -897,9 +901,9 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
result = kctl->put(kctl, control); result = kctl->put(kctl, control);
} }
if (result > 0) { if (result > 0) {
struct snd_ctl_elem_id id = control->id;
up_read(&card->controls_rwsem); up_read(&card->controls_rwsem);
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
&control->id);
return 0; return 0;
} }
} }
@ -1333,8 +1337,9 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
} }
err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv); err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
if (err > 0) { if (err > 0) {
struct snd_ctl_elem_id id = kctl->id;
up_read(&card->controls_rwsem); up_read(&card->controls_rwsem);
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &kctl->id); snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
return 0; return 0;
} }
} else { } else {