From 07b9f12864d16c3a861aef4817eb1efccbc5d0e6 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Tue, 19 Dec 2017 11:14:42 +0200
Subject: [PATCH] USB: Fix off by one in type-specific length check of BOS SSP
 capability
Git-commit: 07b9f12864d16c3a861aef4817eb1efccbc5d0e6
Patch-mainline: v4.15-rc6
References: bsc#1085539

USB 3.1 devices are not detected as 3.1 capable since 4.15-rc3 due to a
off by one in commit 81cf4a45360f ("USB: core: Add type-specific length
check of BOS descriptors")

It uses USB_DT_USB_SSP_CAP_SIZE() to get SSP capability size which takes
the zero based SSAC as argument, not the actual count of sublink speed
attributes.

USB3 spec 9.6.2.5 says "The number of Sublink Speed Attributes = SSAC + 1."

The type-specific length check patch was added to stable and needs to be
fixed there as well

Fixes: 81cf4a45360f ("USB: core: Add type-specific length check of BOS descriptors")
Cc: linux-stable <stable@vger.kernel.org>
CC: Masakazu Mokuno <masakazu.mokuno@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/core/config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 78e92d29f8d9..c821b4b9647e 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -1007,7 +1007,7 @@ int usb_get_bos_descriptor(struct usb_device *dev)
 		case USB_SSP_CAP_TYPE:
 			ssp_cap = (struct usb_ssp_cap_descriptor *)buffer;
 			ssac = (le32_to_cpu(ssp_cap->bmAttributes) &
-				USB_SSP_SUBLINK_SPEED_ATTRIBS) + 1;
+				USB_SSP_SUBLINK_SPEED_ATTRIBS);
 			if (length >= USB_DT_USB_SSP_CAP_SIZE(ssac))
 				dev->bos->ssp_cap = ssp_cap;
 			break;
-- 
2.13.6