From 976a68f06b2ea49e2ab67a5f84919a8b105db8be Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 14 Nov 2019 17:56:12 +0100
Subject: [PATCH] ALSA: usb-audio: Fix incorrect size check for processing/extension units
Git-commit: 976a68f06b2ea49e2ab67a5f84919a8b105db8be
Patch-mainline: v5.4-rc8
References: git-fixes

The recently introduced unit descriptor validation had some bug for
processing and extension units, it counts a bControlSize byte twice so
it expected a bigger size than it should have been.  This seems
resulting in a probe error on a few devices.

Fix the calculation for proper checks of PU and EU.

Fixes: 57f8770620e9 ("ALSA: usb-audio: More validations of descriptor units")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191114165613.7422-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/usb/validate.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/usb/validate.c b/sound/usb/validate.c
index a5e584b60dcd..389e8657434a 100644
--- a/sound/usb/validate.c
+++ b/sound/usb/validate.c
@@ -81,9 +81,9 @@ static bool validate_processing_unit(const void *p,
 	switch (v->protocol) {
 	case UAC_VERSION_1:
 	default:
-		/* bNrChannels, wChannelConfig, iChannelNames, bControlSize */
-		len += 1 + 2 + 1 + 1;
-		if (d->bLength < len) /* bControlSize */
+		/* bNrChannels, wChannelConfig, iChannelNames */
+		len += 1 + 2 + 1;
+		if (d->bLength < len + 1) /* bControlSize */
 			return false;
 		m = hdr[len];
 		len += 1 + m + 1; /* bControlSize, bmControls, iProcessing */
-- 
2.16.4