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

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>
imx_4.1.15_1.0.0_ga
Lars-Peter Clausen 6 years ago
committed by Takashi Iwai
parent
commit
fd9f26e4ec
1 changed files with 10 additions and 5 deletions
  1. +10
    -5
      sound/core/control.c

+ 10
- 5
sound/core/control.c View File

@ -330,6 +330,7 @@ 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)
@ -358,8 +359,9 @@ 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;
@ -388,6 +390,7 @@ int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
bool add_on_replace)
{
struct snd_ctl_elem_id id;
unsigned int count;
unsigned int idx;
struct snd_kcontrol *old;
int ret;
@ -423,8 +426,9 @@ add:
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;
@ -897,9 +901,9 @@ 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;
}
}
@ -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);
if (err > 0) {
struct snd_ctl_elem_id id = kctl->id;
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;
}
} else {


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