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cdc-acm: add sanity checks

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Check the special CDC headers for a plausible minimum length.
Another big operating systems ignores such garbage.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
CC: stable@vger.kernel.org
Reviewed-by: Adam Lee <adam8157@gmail.com>
Tested-by: Adam Lee <adam8157@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2015-01-28 11:14:55 +01:00 • committed by Greg Kroah-Hartman
parent 6b629f2826
commit 7e860a6e7a
1 changed files with 16 additions and 5 deletions
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21
drivers/usb/class/cdc-acm.c
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@ -1091,6 +1091,7 @@ static int acm_probe(struct usb_interface *intf,
unsigned long quirks; unsigned long quirks;
int num_rx_buf; int num_rx_buf;
int i; int i;
unsigned int elength = 0;
int combined_interfaces = 0; int combined_interfaces = 0;
struct device *tty_dev; struct device *tty_dev;
int rv = -ENOMEM; int rv = -ENOMEM;
@ -1136,9 +1137,12 @@ static int acm_probe(struct usb_interface *intf,
dev_err(&intf->dev, "skipping garbage\n"); dev_err(&intf->dev, "skipping garbage\n");
goto next_desc; goto next_desc;
} }
elength = buffer[0];
switch (buffer[2]) { switch (buffer[2]) {
case USB_CDC_UNION_TYPE: /* we've found it */ case USB_CDC_UNION_TYPE: /* we've found it */
if (elength < sizeof(struct usb_cdc_union_desc))
goto next_desc;
if (union_header) { if (union_header) {
dev_err(&intf->dev, "More than one " dev_err(&intf->dev, "More than one "
"union descriptor, skipping ...\n"); "union descriptor, skipping ...\n");
@ -1147,29 +1151,36 @@ static int acm_probe(struct usb_interface *intf,
union_header = (struct usb_cdc_union_desc *)buffer; union_header = (struct usb_cdc_union_desc *)buffer;
break; break;
case USB_CDC_COUNTRY_TYPE: /* export through sysfs*/ 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; cfd = (struct usb_cdc_country_functional_desc *)buffer;
break; break;
case USB_CDC_HEADER_TYPE: /* maybe check version */ case USB_CDC_HEADER_TYPE: /* maybe check version */
break; /* for now we ignore it */ break; /* for now we ignore it */
case USB_CDC_ACM_TYPE: case USB_CDC_ACM_TYPE:
if (elength < 4)
goto next_desc;
ac_management_function = buffer[3]; ac_management_function = buffer[3];
break; break;
case USB_CDC_CALL_MANAGEMENT_TYPE: case USB_CDC_CALL_MANAGEMENT_TYPE:
if (elength < 5)
goto next_desc;
call_management_function = buffer[3]; call_management_function = buffer[3];
call_interface_num = buffer[4]; call_interface_num = buffer[4];
break; break;
default: default:
/* there are LOTS more CDC descriptors that /*
* there are LOTS more CDC descriptors that
* could legitimately be found here. * could legitimately be found here.
*/ */
dev_dbg(&intf->dev, "Ignoring descriptor: " dev_dbg(&intf->dev, "Ignoring descriptor: "
"type %02x, length %d\n", "type %02x, length %ud\n",
buffer[2], buffer[0]); buffer[2], elength);
break; break;
} }
next_desc: next_desc:
buflen -= buffer[0]; buflen -= elength;
buffer += buffer[0]; buffer += elength;
} }
if (!union_header) { if (!union_header) {