[3.16.y-ckt stable] Patch "ALSA: usb-audio: Fix NULL dereference in create_fixed_stream_quirk()" has been added to the 3.16.y-ckt tree

Luis Henriques luis.henriques at canonical.com
Wed Mar 30 13:55:29 UTC 2016


This is a note to let you know that I have just added a patch titled

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

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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

>From b92dbabac3053baaf83bcae270bf058cd5839e35 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Tue, 15 Mar 2016 12:09:10 +0100
Subject: 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 at suse.de>
Cc: Moritz Muehlenhoff <jmm at inutil.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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)




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