From: Bjørn Mork Date: Fri, 20 Jan 2012 00:49:57 +0000 (+0100) Subject: USB: cdc-wdm: Avoid hanging on interface with no USB_CDC_DMM_TYPE X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=7e3054a005537f28544ab2870c375458362f7473;p=linux-beck.git USB: cdc-wdm: Avoid hanging on interface with no USB_CDC_DMM_TYPE 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, revision 1.1 Signed-off-by: Bjørn Mork Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index bb8208a13a53..c0197af22fd8 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -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 static DEFINE_MUTEX(wdm_mutex); @@ -602,7 +604,7 @@ static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id) struct usb_cdc_dmm_desc *dmhd; u8 *buffer = intf->altsetting->extra; int buflen = intf->altsetting->extralen; - u16 maxcom = 0; + u16 maxcom = WDM_DEFAULT_BUFSIZE; if (!buffer) goto out;