[PATCH] USB: Do not pass negative length to snoop_urb()

[Michal Sojka]

When `echo Y > /sys/module/usbcore/parameters/usbfs_snoop` and
usb_control_msg() returns error, a lot of kernel memory is dumped to dmesg
until unhandled kernel paging request occurs.

Signed-off-by: Michal Sojka <sojkam1@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
---
 drivers/usb/core/devio.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index a7131ad..37518df 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -802,7 +802,7 @@ static int proc_control(struct dev_state *ps, void __user *arg)
 				    tbuf, ctrl.wLength, tmo);
 		usb_lock_device(dev);
 		snoop_urb(dev, NULL, pipe, max(i, 0), min(i, 0), COMPLETE,
-			tbuf, i);
+			  tbuf, max(i, 0));
 		if ((i > 0) && ctrl.wLength) {
 			if (copy_to_user(ctrl.data, tbuf, i)) {
 				free_page((unsigned long)tbuf);
-- 
1.7.2.3

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