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authorLars-Peter Clausen <lars@metafoo.de>2014-06-18 13:32:34 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-26 15:10:29 -0400
commitab59a4b59f1e0aa0b2279be893a39a406c938c21 (patch)
parent291cd312b3c2826892299a74249fc9a88fb3305f (diff)
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 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/core/control.c b/sound/core/control.c
index 4c8d9e34872d..3970a9907985 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) {