ALSA: usb-audio: Add sanity checks for endpoint accesses

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
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 2ed260b10f6dc02cd129550ba1067c878034cb07..7ccbcaf6a1476423e0d2becf0bf91f3463a47b46 100644 (file)
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -285,6 +285,8 @@ 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 7b1cb365ffab74d6028206adb8012226da963bac..c07a7eda42a28eee533752e28f787ccfd2230ed2 100644 (file)
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -438,6 +438,9 @@ 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 279025650568ec2936e270d33a1737fd5f504cd6..f6c3bf79af9a7d9f7cabe6b83c3573a59964b826 100644 (file)
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1519,7 +1519,11 @@ 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(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(chip->dev,

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 9245f52d43bdecfeb710b6cfc6ae99b3202aae90..44d178ee9177565bba3fde9d2ac2b7308e8dd7ae 100644 (file)
--- 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;