[ 3.5.y.z extended stable ] Patch "ALSA: usb-audio: fix invalid length check for RME and other" has been added to staging queue

[Herton Ronaldo Krzesinski]

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

    ALSA: usb-audio: fix invalid length check for RME and other

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

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

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 23bef2be1f2e27b09d4186009285bc6bd0742568 Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens at ladisch.de>
Date: Thu, 29 Nov 2012 17:04:23 +0100
Subject: [PATCH] ALSA: usb-audio: fix invalid length check for RME and other
 UAC 2 devices

commit d56268fb108c7c21e19933588ca4d94652585183 upstream.

Commit 23caaf19b11e (ALSA: usb-mixer: Add support for Audio Class v2.0)
forgot to adjust the length check for UAC 2.0 feature unit descriptors.
This would make the code abort on encountering a feature unit without
per-channel controls, and thus prevented the driver to work with any
device having such a unit, such as the RME Babyface or Fireface UCX.

Reported-by: Florian Hanisch <fhanisch at uni-potsdam.de>
Tested-by: Matthew Robbetts <wingfeathera at gmail.com>
Tested-by: Michael Beer <beerml at sigma6audio.de>
Cc: Daniel Mack <daniel at caiaq.de>
Signed-off-by: Clemens Ladisch <clemens at ladisch.de>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 sound/usb/mixer.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 298070e..41e8bfb 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1259,16 +1259,23 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
 		}
 		channels = (hdr->bLength - 7) / csize - 1;
 		bmaControls = hdr->bmaControls;
+		if (hdr->bLength < 7 + csize) {
+			snd_printk(KERN_ERR "usbaudio: unit %u: "
+				   "invalid UAC_FEATURE_UNIT descriptor\n",
+				   unitid);
+			return -EINVAL;
+		}
 	} else {
 		struct uac2_feature_unit_descriptor *ftr = _ftr;
 		csize = 4;
 		channels = (hdr->bLength - 6) / 4 - 1;
 		bmaControls = ftr->bmaControls;
-	}
-
-	if (hdr->bLength < 7 || !csize || hdr->bLength < 7 + csize) {
-		snd_printk(KERN_ERR "usbaudio: unit %u: invalid UAC_FEATURE_UNIT descriptor\n", unitid);
-		return -EINVAL;
+		if (hdr->bLength < 6 + csize) {
+			snd_printk(KERN_ERR "usbaudio: unit %u: "
+				   "invalid UAC_FEATURE_UNIT descriptor\n",
+				   unitid);
+			return -EINVAL;
+		}
 	}

 	/* parse the source unit */
--
1.7.9.5