Commit 332f989a authored by Oliver Neukum's avatar Oliver Neukum Committed by David S. Miller
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CDC-NCM: handle incomplete transfer of MTU

A malicious device may give half an answer when asked
for its MTU. The driver will proceed after this with
a garbage MTU. Anything but a complete answer must be treated
as an error.

V2: used sizeof as request by Alexander

Signed-off-by: default avatarOliver Neukum <>
Signed-off-by: default avatarDavid S. Miller <>
parent 025ec40b
......@@ -578,8 +578,8 @@ static void cdc_ncm_set_dgram_size(struct usbnet *dev, int new_size)
/* read current mtu value from device */
err = usbnet_read_cmd(dev, USB_CDC_GET_MAX_DATAGRAM_SIZE,
0, iface_no, &max_datagram_size, 2);
if (err < 0) {
0, iface_no, &max_datagram_size, sizeof(max_datagram_size));
if (err < sizeof(max_datagram_size)) {
dev_dbg(&dev->intf->dev, "GET_MAX_DATAGRAM_SIZE failed\n");
goto out;
......@@ -590,7 +590,7 @@ static void cdc_ncm_set_dgram_size(struct usbnet *dev, int new_size)
max_datagram_size = cpu_to_le16(ctx->max_datagram_size);
err = usbnet_write_cmd(dev, USB_CDC_SET_MAX_DATAGRAM_SIZE,
0, iface_no, &max_datagram_size, 2);
0, iface_no, &max_datagram_size, sizeof(max_datagram_size));
if (err < 0)
dev_dbg(&dev->intf->dev, "SET_MAX_DATAGRAM_SIZE failed\n");
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