On Fri, 2015-01-23 at 23:08 +0800, Adam Lee wrote:
Hi,
could you test and review this?
Regards
Oliver
>From 1ddabb5731135fe43f67f3b4645445c2de06dada Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@xxxxxxx>
Date: Tue, 13 Jan 2015 16:55:52 +0100
Subject: [PATCH] cdc-acm: add sanity checks
Check the special CDC headers for a plausible minimum length.
Another big operating systems ignores such garbage.
Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
---
drivers/usb/class/cdc-acm.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 546a17e8..3dd540d 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1091,6 +1091,7 @@ static int acm_probe(struct usb_interface *intf,
unsigned long quirks;
int num_rx_buf;
int i;
+ unsigned int elength = 0;
int combined_interfaces = 0;
struct device *tty_dev;
int rv = -ENOMEM;
@@ -1136,9 +1137,12 @@ static int acm_probe(struct usb_interface *intf,
dev_err(&intf->dev, "skipping garbage\n");
goto next_desc;
}
+ elength = buffer[0];
switch (buffer[2]) {
case USB_CDC_UNION_TYPE: /* we've found it */
+ if (elength < sizeof(struct usb_cdc_union_desc))
+ goto next_desc;
if (union_header) {
dev_err(&intf->dev, "More than one "
"union descriptor, skipping ...\n");
@@ -1147,29 +1151,36 @@ static int acm_probe(struct usb_interface *intf,
union_header = (struct usb_cdc_union_desc *)buffer;
break;
case USB_CDC_COUNTRY_TYPE: /* export through sysfs*/
+ if (elength < sizeof(struct usb_cdc_country_functional_desc))
+ goto next_desc;
cfd = (struct usb_cdc_country_functional_desc *)buffer;
break;
case USB_CDC_HEADER_TYPE: /* maybe check version */
break; /* for now we ignore it */
case USB_CDC_ACM_TYPE:
+ if (elength < 4)
+ goto next_desc;
ac_management_function = buffer[3];
break;
case USB_CDC_CALL_MANAGEMENT_TYPE:
+ if (elength < 5)
+ goto next_desc;
call_management_function = buffer[3];
call_interface_num = buffer[4];
break;
default:
- /* there are LOTS more CDC descriptors that
+ /*
+ * there are LOTS more CDC descriptors that
* could legitimately be found here.
*/
dev_dbg(&intf->dev, "Ignoring descriptor: "
- "type %02x, length %d\n",
- buffer[2], buffer[0]);
+ "type %02x, length %ud\n",
+ buffer[2], elength);
break;
}
next_desc:
- buflen -= buffer[0];
- buffer += buffer[0];
+ buflen -= elength;
+ buffer += elength;
}
if (!union_header) {
--
1.8.4.5
