From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lars-Peter Clausen , Jaroslav Kysela , Takashi Iwai Subject: [PATCH 3.4 21/26] ALSA: control: Dont access controls outside of protected regions Date: Tue, 24 Jun 2014 11:50:44 -0400 Message-Id: <20140624154620.511454083@linuxfoundation.org> In-Reply-To: <20140624154619.499002156@linuxfoundation.org> References: <20140624154619.499002156@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lars-Peter Clausen 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 Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/control.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) --- a/sound/core/control.c +++ b/sound/core/control.c @@ -329,6 +329,7 @@ int snd_ctl_add(struct snd_card *card, s { struct snd_ctl_elem_id id; unsigned int idx; + unsigned int count; int err = -EINVAL; if (! kcontrol) @@ -357,8 +358,9 @@ int snd_ctl_add(struct snd_card *card, s 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; @@ -387,6 +389,7 @@ int snd_ctl_replace(struct snd_card *car bool add_on_replace) { struct snd_ctl_elem_id id; + unsigned int count; unsigned int idx; struct snd_kcontrol *old; int ret; @@ -422,8 +425,9 @@ 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; @@ -894,9 +898,9 @@ static int snd_ctl_elem_write(struct snd 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; } } @@ -1330,8 +1334,9 @@ static int snd_ctl_tlv_ioctl(struct snd_ } 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 {