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Subject[PATCH 4.9 105/109] USB: core: Add type-specific length check of BOS descriptors
Date
4.9-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
@@ -900,14 +900,25 @@ 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);
@@ -960,7 +971,13 @@ 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) {
@@ -968,7 +985,7 @@ 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;
@@ -981,8 +998,11 @@ 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
@@ -854,6 +854,8 @@ 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

@@ -1046,6 +1048,7 @@ 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].

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