linux-kernel - [PATCH 4.9 094/164] USB: hub: fix SS hub-descriptor handling

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Message-Id: <20170523200911.207939833@linuxfoundation.org>
Date:   Tue, 23 May 2017 22:08:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, John Youn <John.Youn@...opsys.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Johan Hovold <johan@...nel.org>
Subject: [PATCH 4.9 094/164] USB: hub: fix SS hub-descriptor handling

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@...nel.org>

commit 2c25a2c818023df64463aac3288a9f969491e507 upstream.

A SuperSpeed hub descriptor does not have any variable-length fields so
bail out when reading a short descriptor.

This avoids parsing and leaking two bytes of uninitialised slab data
through sysfs removable-attributes.

Fixes: dbe79bbe9dcb ("USB 3.0 Hub Changes")
Cc: John Youn <John.Youn@...opsys.com>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Johan Hovold <johan@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/usb/core/hub.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -378,8 +378,12 @@ static int get_hub_descriptor(struct usb
 			USB_REQ_GET_DESCRIPTOR, USB_DIR_IN | USB_RT_HUB,
 			dtype << 8, 0, data, size,
 			USB_CTRL_GET_TIMEOUT);
-		if (ret >= (USB_DT_HUB_NONVAR_SIZE + 2))
+		if (hub_is_superspeed(hdev)) {
+			if (ret == size)
+				return ret;
+		} else if (ret >= (USB_DT_HUB_NONVAR_SIZE + 2)) {
 			return ret;
+		}
 	}
 	return -EINVAL;
 }
@@ -1319,7 +1323,7 @@ static int hub_configure(struct usb_hub
 
 	/* Request the entire hub descriptor.
 	 * hub->descriptor can handle USB_MAXCHILDREN ports,
-	 * but the hub can/will return fewer bytes here.
+	 * but a (non-SS) hub can/will return fewer bytes here.
 	 */
 	ret = get_hub_descriptor(hdev, hub->descriptor);
 	if (ret < 0) {