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    Subject[PATCH 4.9 044/138] ALSA: usb-audio: Add sanity checks to FE parser
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: Takashi Iwai <tiwai@suse.de>

    commit d937cd6790a2bef2d07b500487646bd794c039bb upstream.

    When the usb-audio descriptor contains the malformed feature unit
    description with a too short length, the driver may access
    out-of-bounds. Add a sanity check of the header size at the beginning
    of parse_audio_feature_unit().

    Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
    Reported-by: Andrey Konovalov <andreyknvl@google.com>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    sound/usb/mixer.c | 12 ++++++++++++
    1 file changed, 12 insertions(+)

    --- a/sound/usb/mixer.c
    +++ b/sound/usb/mixer.c
    @@ -1463,6 +1463,12 @@ static int parse_audio_feature_unit(stru
    __u8 *bmaControls;

    if (state->mixer->protocol == UAC_VERSION_1) {
    + if (hdr->bLength < 7) {
    + usb_audio_err(state->chip,
    + "unit %u: invalid UAC_FEATURE_UNIT descriptor\n",
    + unitid);
    + return -EINVAL;
    + }
    csize = hdr->bControlSize;
    if (!csize) {
    usb_audio_dbg(state->chip,
    @@ -1480,6 +1486,12 @@ static int parse_audio_feature_unit(stru
    }
    } else {
    struct uac2_feature_unit_descriptor *ftr = _ftr;
    + if (hdr->bLength < 6) {
    + usb_audio_err(state->chip,
    + "unit %u: invalid UAC_FEATURE_UNIT descriptor\n",
    + unitid);
    + return -EINVAL;
    + }
    csize = 4;
    channels = (hdr->bLength - 6) / 4 - 1;
    bmaControls = ftr->bmaControls;

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