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Date: Mon, 11 Nov 2019 19:27:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Oliver Neukum <oneukum@...e.com>,
"David S. Miller" <davem@...emloft.net>,
syzbot+0631d878823ce2411636@...kaller.appspotmail.com
Subject: [PATCH 4.19 002/125] CDC-NCM: handle incomplete transfer of MTU
From: Oliver Neukum <oneukum@...e.com>
[ Upstream commit 332f989a3b0041b810836c5c3747e59aad7e9d0b ]
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
Reported-and-tested-by: syzbot+0631d878823ce2411636@...kaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@...e.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/net/usb/cdc_ncm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -578,8 +578,8 @@ static void cdc_ncm_set_dgram_size(struc
/* read current mtu value from device */
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, 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(struc
max_datagram_size = cpu_to_le16(ctx->max_datagram_size);
err = usbnet_write_cmd(dev, USB_CDC_SET_MAX_DATAGRAM_SIZE,
USB_TYPE_CLASS | USB_DIR_OUT | USB_RECIP_INTERFACE,
- 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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