USB: core: Add type-specific length check of BOS descriptors

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 <[e-mail]>
Cc: stable <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/config.c

···
 	}
 }
 
+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);
···
 			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) {
···
 			continue;
 		}
 
-		switch (cap->bDevCapabilityType) {
+		switch (cap_type) {
 		case USB_CAP_TYPE_WIRELESS_USB:
 			/* Wireless USB cap descriptor is handled by wusb */
 			break;
···
 				(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 =

include/uapi/linux/usb/ch9.h

···
 	__u8  bReserved;
 } __attribute__((packed));
 
+#define USB_DT_USB_WIRELESS_CAP_SIZE	11
+
 /* USB 2.0 Extension descriptor */
 #define	USB_CAP_TYPE_EXT		2
 
···
 	__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].