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authorLars-Peter Clausen <lars@metafoo.de>2014-06-18 13:32:34 +0200
committerTakashi Iwai <tiwai@suse.de>2014-06-18 15:13:23 +0200
commitac902c112d90a89e59916f751c2745f4dbdbb4bd (patch)
treedcf1e049671b65d03cce48a8a9d836c3fa6d14f0 /sound/core
parentfd9f26e4eca5d08a27d12c0933fceef76ed9663d (diff)
ALSA: control: Handle numid overflow
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 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/core')
-rw-r--r--sound/core/control.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/control.c b/sound/core/control.c
index 5c49f976fc7b..8d6e4bae7407 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -288,6 +288,10 @@ 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) {