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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 15:15:43 -0400
commit8e1853b436edc41ee4e0214cf5a2fc04201915f8 (patch)
tree65198d0a12e90899ad297003f761226ddbc28ce2
parent1637a83bb15491efb3e7c8cd746471ef3710e79d (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>
-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 d4a597fe86e4..93215b4bec6b 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) {