netdev - [PATCH v2] USB: hso: Fix OOB memory access in hso_probe/hso_get_config

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Message-ID: <20181210080443.GA27035@kroah.com>
Date:   Mon, 10 Dec 2018 09:04:43 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     linux-usb@...r.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Hui Peng <benquike@...il.com>,
        Mathias Payer <mathias.payer@...elwelt.net>
Subject: [PATCH v2] USB: hso: Fix OOB memory access in
 hso_probe/hso_get_config_data

From: Hui Peng <benquike@...il.com>

The function hso_probe reads if_num from the USB device (as an u8) and uses
it without a length check to index an array, resulting in an OOB memory read
in hso_probe or hso_get_config_data. Added a length check for both locations
and updated hso_probe to bail on error.

This issue has been assigned CVE-2018-19985.

Reported-by: Hui Peng <benquike@...il.com>
Reported-by: Mathias Payer <mathias.payer@...elwelt.net>
Signed-off-by: Hui Peng <benquike@...il.com>
Signed-off-by: Mathias Payer <mathias.payer@...elwelt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
v2: fixed error check to just be < 0
    Added CVE to changelog text

 drivers/net/usb/hso.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 184c24baca15..d6916f787fce 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2807,6 +2807,12 @@ static int hso_get_config_data(struct usb_interface *interface)
 		return -EIO;
 	}
 
+	/* check if we have a valid interface */
+	if (if_num > 16) {
+		kfree(config_data);
+		return -EINVAL;
+	}
+
 	switch (config_data[if_num]) {
 	case 0x0:
 		result = 0;
@@ -2877,10 +2883,18 @@ static int hso_probe(struct usb_interface *interface,
 
 	/* Get the interface/port specification from either driver_info or from
 	 * the device itself */
-	if (id->driver_info)
+	if (id->driver_info) {
+		/* if_num is controlled by the device, driver_info is a 0 terminated
+		 * array. Make sure, the access is in bounds! */
+		for (i = 0; i <= if_num; ++i)
+			if (((u32 *)(id->driver_info))[i] == 0)
+				goto exit;
 		port_spec = ((u32 *)(id->driver_info))[if_num];
-	else
+	} else {
 		port_spec = hso_get_config_data(interface);
+		if (port_spec < 0)
+			goto exit;
+	}
 
 	/* Check if we need to switch to alt interfaces prior to port
 	 * configuration */
-- 
2.19.2