From 873156565ca67779bbf5a3475ccd08ea3bb92522 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 15 Mar 2016 15:20:58 +0100
Subject: [PATCH 2/2] 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>
---
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 2ed260b10f6d..7ccbcaf6a147 100644
--- 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 e6f71894ecdc..c2131b851602 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -415,6 +415,9 @@ 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 d3608c0a29f3..2d724e3c4cc0 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1518,7 +1518,11 @@ 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 cdac5179db3f..4da64896df6d 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;
--
2.5.0