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    Subject[PATCH 3.12 59/98] ALSA: usb-audio: Add sanity checks for endpoint accesses
    Date
    From: Takashi Iwai <tiwai@suse.de>

    3.12-stable review patch. If anyone has any objections, please let me know.

    ===============

    commit 447d6275f0c21f6cc97a88b3a0c601436a4cdf2a upstream.

    Add some sanity check codes before actually accessing the endpoint via
    get_endpoint() in order to avoid the invalid access through a
    malformed USB descriptor. Mostly just checking bNumEndpoints, but in
    one place (snd_microii_spdif_default_get()), the validity of iface and
    altsetting index is checked as well.

    Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=971125
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    ---
    sound/usb/clock.c | 2 ++
    sound/usb/endpoint.c | 3 +++
    sound/usb/mixer_quirks.c | 4 ++++
    sound/usb/pcm.c | 2 ++
    4 files changed, 11 insertions(+)

    diff --git a/sound/usb/clock.c b/sound/usb/clock.c
    index 86f80c60b21f..1329d7725196 100644
    --- a/sound/usb/clock.c
    +++ b/sound/usb/clock.c
    @@ -283,6 +283,8 @@ static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
    unsigned char data[3];
    int err, crate;

    + if (get_iface_desc(alts)->bNumEndpoints < 1)
    + return -EINVAL;
    ep = get_endpoint(alts, 0)->bEndpointAddress;

    /* if endpoint doesn't have sampling rate control, bail out */
    diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
    index b0a0f2028319..c42a4c0e95da 100644
    --- a/sound/usb/endpoint.c
    +++ b/sound/usb/endpoint.c
    @@ -410,6 +410,9 @@ exit_clear:
    *
    * New endpoints will be added to chip->ep_list and must be freed by
    * calling snd_usb_endpoint_free().
    + *
    + * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
    + * bNumEndpoints > 1 beforehand.
    */
    struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
    struct usb_host_interface *alts,
    diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
    index ca2d07378807..ee4b3b901bf5 100644
    --- a/sound/usb/mixer_quirks.c
    +++ b/sound/usb/mixer_quirks.c
    @@ -1372,7 +1372,11 @@ static int snd_microii_spdif_default_get(struct snd_kcontrol *kcontrol,

    /* use known values for that card: interface#1 altsetting#1 */
    iface = usb_ifnum_to_if(mixer->chip->dev, 1);
    + if (!iface || iface->num_altsetting < 2)
    + return -EINVAL;
    alts = &iface->altsetting[1];
    + if (get_iface_desc(alts)->bNumEndpoints < 1)
    + return -EINVAL;
    ep = get_endpoint(alts, 0)->bEndpointAddress;

    err = snd_usb_ctl_msg(mixer->chip->dev,
    diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
    index 98ca3540514f..1f498b1f88bd 100644
    --- a/sound/usb/pcm.c
    +++ b/sound/usb/pcm.c
    @@ -159,6 +159,8 @@ static int init_pitch_v1(struct snd_usb_audio *chip, int iface,
    unsigned char data[1];
    int err;

    + if (get_iface_desc(alts)->bNumEndpoints < 1)
    + return -EINVAL;
    ep = get_endpoint(alts, 0)->bEndpointAddress;

    data[0] = 1;
    --
    2.8.1
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