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authorBjørn Mork <bjorn@mork.no>2012-01-20 04:49:57 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2012-01-25 02:43:13 +0400
commit7e3054a005537f28544ab2870c375458362f7473 (patch)
tree39e3b0522fe85b28f5cd80dce52139c7639e1525 /drivers/usb/class
parent8143a8963c374116f84aba15dcaeaf02370c8098 (diff)
downloadlinux-7e3054a005537f28544ab2870c375458362f7473.tar.xz
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 <bjorn@mork.no> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/class')
-rw-r--r--drivers/usb/class/cdc-wdm.c4
1 files changed, 3 insertions, 1 deletions
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;