From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 15 Mar 2016 11:09:10 +0000 (+0100)
Subject: ALSA: usb-audio: Fix NULL dereference in create_fixed_stream_quirk()
X-Git-Tag: v3.16.35~230
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b92dbabac3053baaf83bcae270bf058cd5839e35;p=thirdparty%2Fkernel%2Fstable.git

ALSA: usb-audio: Fix NULL dereference in create_fixed_stream_quirk()

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@suse.de>
Cc: Moritz Muehlenhoff <jmm@inutil.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 0980405f987a8..a8e3fb4c2e111 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)