[PATCH 4.9 148/222] net: cdc_ncm: Signedness bug in cdc_ncm_set_dgram_size()

From: Greg Kroah-Hartman
Date: Fri Nov 22 2019 - 05:45:52 EST


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit a56dcc6b455830776899ce3686735f1172e12243 upstream.

This code is supposed to test for negative error codes and partial
reads, but because sizeof() is size_t (unsigned) type then negative
error codes are type promoted to high positive values and the condition
doesn't work as expected.

Fixes: 332f989a3b00 ("CDC-NCM: handle incomplete transfer of MTU")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/net/usb/cdc_ncm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -577,7 +577,7 @@ static void cdc_ncm_set_dgram_size(struc
err = usbnet_read_cmd(dev, USB_CDC_GET_MAX_DATAGRAM_SIZE,
USB_TYPE_CLASS | USB_DIR_IN | USB_RECIP_INTERFACE,
0, iface_no, &max_datagram_size, sizeof(max_datagram_size));
- if (err < sizeof(max_datagram_size)) {
+ if (err != sizeof(max_datagram_size)) {
dev_dbg(&dev->intf->dev, "GET_MAX_DATAGRAM_SIZE failed\n");
goto out;
}