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    Subject[PATCH 3.14 67/68] ALSA: control: Handle numid overflow
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Lars-Peter Clausen <lars@metafoo.de>

    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>

    ---
    sound/core/control.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/sound/core/control.c
    +++ b/sound/core/control.c
    @@ -289,6 +289,10 @@ static bool snd_ctl_remove_numid_conflic
    {
    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) {



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