[68/89] USB: cdc-wdm: Avoid hanging on interface with no USB_CDC_DMM_TYPE
From: Greg KH
Date: Wed Feb 01 2012 - 16:20:55 EST
3.2-stable review patch. If anyone has any objections, please let me know.
From: BjÃ¸rn Mork <bjorn@xxxxxxx>
commit 15699e6fafc3a90e5fdc2ef30555a04dee62286f upstream.
The probe does not strictly require the USB_CDC_DMM_TYPE
descriptor, which is a good thing as it makes the driver
usable on non-conforming interfaces. A user could e.g.
bind to it to a CDC ECM interface by using the new_id and
bind sysfs files. But this would fail with a 0 buffer length
due to the missing descriptor.
Fix by defining a reasonable fallback size: The minimum
device receive buffer size required by the CDC WMC standard,
Signed-off-by: BjÃ¸rn Mork <bjorn@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/usb/class/cdc-wdm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
@@ -57,6 +57,8 @@ MODULE_DEVICE_TABLE (usb, wdm_ids);
#define WDM_MAX 16
+/* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
+#define WDM_DEFAULT_BUFSIZE 256
@@ -636,7 +638,7 @@ static int wdm_probe(struct usb_interfac
struct usb_cdc_dmm_desc *dmhd;
u8 *buffer = intf->altsetting->extra;
int buflen = intf->altsetting->extralen;
- u16 maxcom = 0;
+ u16 maxcom = WDM_DEFAULT_BUFSIZE;
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/