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authorLars-Peter Clausen <lars@metafoo.de>2014-06-18 13:32:33 +0200
committerTakashi Iwai <tiwai@suse.de>2014-06-18 15:13:07 +0200
commitfd9f26e4eca5d08a27d12c0933fceef76ed9663d (patch)
tree1b68c534f868ec086cf78e864888c99bdb70f5b5 /sound
parent82262a46627bebb0febcc26664746c25cef08563 (diff)
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>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/control.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/sound/core/control.c b/sound/core/control.c
index 1f413c286511..5c49f976fc7b 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -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 {