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From 669982364299f6f22bea4324f0f7ee8f8a361b87 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Wed, 18 Jun 2014 13:32:34 +0200
Subject: [PATCH] ALSA: control: Handle numid overflow
commit ac902c112d90a89e59916f751c2745f4dbdbb4bd upstream.
Each control gets automatically assigned its numids when the control is created.
The allocation is done by incrementing the numid by the amount of allocated
numids per allocation. This means that excessive creation and destruction of
controls (e.g. via SNDRV_CTL_IOCTL_ELEM_ADD/REMOVE) can cause the id to
eventually overflow. Currently when this happens for the control that caused the
overflow kctl->id.numid + kctl->count will also over flow causing it to be
smaller than kctl->id.numid. Most of the code assumes that this is something
that can not happen, so we need to make sure that it won't happen
Fixes CVE-2014-4656
Upstream-Status: Backport
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
sound/core/control.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/sound/core/control.c b/sound/core/control.c
index d4a597f..93215b4 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -289,6 +289,10 @@ static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
{
struct snd_kcontrol *kctl;
+ /* Make sure that the ids assigned to the control do not wrap around */
+ if (card->last_numid >= UINT_MAX - count)
+ card->last_numid = 0;
+
list_for_each_entry(kctl, &card->controls, list) {
if (kctl->id.numid < card->last_numid + 1 + count &&
kctl->id.numid + kctl->count > card->last_numid + 1) {
--
1.9.1
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