[PATCH 3.16.y-ckt 04/17] ALSA: usb-audio: Fix NULL dereference in create_fixed_stream_quirk()

From: Luis Henriques
Date: Tue Apr 12 2016 - 14:08:21 EST


3.16.7-ckt27 -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>
Cc: Moritz Muehlenhoff <jmm@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
sound/usb/quirks.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 0980405f987a..a8e3fb4c2e11 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)