[PATCH 4.14 73/75] USB: core: Add type-specific length check of BOS descriptors - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Masakazu Mokuno <masakazu.mokuno@gmail.com>
Subject: [PATCH 4.14 73/75] USB: core: Add type-specific length check of BOS descriptors
Date: Thu,  7 Dec 2017 14:08:35 +0100	[thread overview]
Message-ID: <20171207130821.764945123@linuxfoundation.org> (raw)
In-Reply-To: <20171207130818.742746317@linuxfoundation.org>

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

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

From: Masakazu Mokuno <masakazu.mokuno@gmail.com>

commit 81cf4a45360f70528f1f64ba018d61cb5767249a upstream.

As most of BOS descriptors are longer in length than their header
'struct usb_dev_cap_header', comparing solely with it is not sufficient
to avoid out-of-bounds access to BOS descriptors.

This patch adds descriptor type specific length check in
usb_get_bos_descriptor() to fix the issue.

Signed-off-by: Masakazu Mokuno <masakazu.mokuno@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/core/config.c    |   28 ++++++++++++++++++++++++----
 include/uapi/linux/usb/ch9.h |    3 +++
 2 files changed, 27 insertions(+), 4 deletions(-)

--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -905,14 +905,25 @@ void usb_release_bos_descriptor(struct u
 	}
 }
 
+static const __u8 bos_desc_len[256] = {
+	[USB_CAP_TYPE_WIRELESS_USB] = USB_DT_USB_WIRELESS_CAP_SIZE,
+	[USB_CAP_TYPE_EXT]          = USB_DT_USB_EXT_CAP_SIZE,
+	[USB_SS_CAP_TYPE]           = USB_DT_USB_SS_CAP_SIZE,
+	[USB_SSP_CAP_TYPE]          = USB_DT_USB_SSP_CAP_SIZE(1),
+	[CONTAINER_ID_TYPE]         = USB_DT_USB_SS_CONTN_ID_SIZE,
+	[USB_PTM_CAP_TYPE]          = USB_DT_USB_PTM_ID_SIZE,
+};
+
 /* Get BOS descriptor set */
 int usb_get_bos_descriptor(struct usb_device *dev)
 {
 	struct device *ddev = &dev->dev;
 	struct usb_bos_descriptor *bos;
 	struct usb_dev_cap_header *cap;
+	struct usb_ssp_cap_descriptor *ssp_cap;
 	unsigned char *buffer;
-	int length, total_len, num, i;
+	int length, total_len, num, i, ssac;
+	__u8 cap_type;
 	int ret;
 
 	bos = kzalloc(sizeof(struct usb_bos_descriptor), GFP_KERNEL);
@@ -965,7 +976,13 @@ int usb_get_bos_descriptor(struct usb_de
 			dev->bos->desc->bNumDeviceCaps = i;
 			break;
 		}
+		cap_type = cap->bDevCapabilityType;
 		length = cap->bLength;
+		if (bos_desc_len[cap_type] && length < bos_desc_len[cap_type]) {
+			dev->bos->desc->bNumDeviceCaps = i;
+			break;
+		}
+
 		total_len -= length;
 
 		if (cap->bDescriptorType != USB_DT_DEVICE_CAPABILITY) {
@@ -973,7 +990,7 @@ int usb_get_bos_descriptor(struct usb_de
 			continue;
 		}
 
-		switch (cap->bDevCapabilityType) {
+		switch (cap_type) {
 		case USB_CAP_TYPE_WIRELESS_USB:
 			/* Wireless USB cap descriptor is handled by wusb */
 			break;
@@ -986,8 +1003,11 @@ int usb_get_bos_descriptor(struct usb_de
 				(struct usb_ss_cap_descriptor *)buffer;
 			break;
 		case USB_SSP_CAP_TYPE:
-			dev->bos->ssp_cap =
-				(struct usb_ssp_cap_descriptor *)buffer;
+			ssp_cap = (struct usb_ssp_cap_descriptor *)buffer;
+			ssac = (le32_to_cpu(ssp_cap->bmAttributes) &
+				USB_SSP_SUBLINK_SPEED_ATTRIBS) + 1;
+			if (length >= USB_DT_USB_SSP_CAP_SIZE(ssac))
+				dev->bos->ssp_cap = ssp_cap;
 			break;
 		case CONTAINER_ID_TYPE:
 			dev->bos->ss_id =
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -876,6 +876,8 @@ struct usb_wireless_cap_descriptor {	/*
 	__u8  bReserved;
 } __attribute__((packed));
 
+#define USB_DT_USB_WIRELESS_CAP_SIZE	11
+
 /* USB 2.0 Extension descriptor */
 #define	USB_CAP_TYPE_EXT		2
 
@@ -1068,6 +1070,7 @@ struct usb_ptm_cap_descriptor {
 	__u8  bDevCapabilityType;
 } __attribute__((packed));
 
+#define USB_DT_USB_PTM_ID_SIZE		3
 /*
  * The size of the descriptor for the Sublink Speed Attribute Count
  * (SSAC) specified in bmAttributes[4:0].
