[PATCH 3.13.y-ckt 51/97] ALSA: usb-audio: Fix NULL dereference in create_fixed_stream_quirk()

From: Kamal Mostafa
Date: Mon Apr 04 2016 - 19:44:30 EST


3.13.11-ckt38 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Takashi Iwai <tiwai@xxxxxxx>

commit 0f886ca12765d20124bd06291c82951fd49a33be upstream.

create_fixed_stream_quirk() may cause a NULL-pointer dereference by
accessing the non-existing endpoint when a USB device with a malformed
USB descriptor is used.

This patch avoids it simply by adding a sanity check of bNumEndpoints
before the accesses.

Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=971125
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
sound/usb/quirks.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 44a04f3..e89156d 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -168,6 +168,12 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
}
alts = &iface->altsetting[fp->altset_idx];
altsd = get_iface_desc(alts);
+ if (altsd->bNumEndpoints < 1) {
+ kfree(fp);
+ kfree(rate_table);
+ return -EINVAL;
+ }
+
fp->protocol = altsd->bInterfaceProtocol;

if (fp->datainterval == 0)
--
2.7.4