HID: usbhid: Fix warning caused by 0-length input reports

Syzbot found a warning caused by hid_submit_ctrl() submitting a
control request to transfer a 0-length input report:

	usb 1-1: BOGUS control dir, pipe 80000280 doesn't match bRequestType a1

(The warning message is a little difficult to understand.  It means
that the control request claims to be for an IN transfer but this
contradicts the USB spec, which requires 0-length control transfers
always to be in the OUT direction.)

Now, a zero-length report isn't good for anything and there's no
reason for a device to have one, but the fuzzer likes to pick out
these weird edge cases.  In the future, perhaps we will decide to
reject 0-length reports at probe time.  For now, the simplest approach
for avoiding these warnings is to pretend that the report actually has
length 1.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: syzbot+9b57a46bf1801ce2a2ca@syzkaller.appspotmail.com
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 6b86908..c56cb03 100644 (file)
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -389,6 +389,7 @@ static int hid_submit_ctrl(struct hid_device *hid)
                maxpacket = usb_maxpacket(hid_to_usb_dev(hid),
                                          usbhid->urbctrl->pipe, 0);
                if (maxpacket > 0) {
+                       len += (len == 0);    /* Don't allow 0-length reports */
                        len = DIV_ROUND_UP(len, maxpacket);
                        len *= maxpacket;
                        if (len > usbhid->bufsize)