Commit 27febbf1 authored Sep 18, 2019 by Bjørn Mork Committed by Greg Kroah-Hartman Oct 05, 2019

cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize



[ Upstream commit 3fe4b3351301660653a2bc73f2226da0ebd2b95e ]

Endpoints with zero wMaxPacketSize are not usable for transferring
data. Ignore such endpoints when looking for valid in, out and
status pipes, to make the driver more robust against invalid and
meaningless descriptors.

The wMaxPacketSize of the out pipe is used as divisor. So this change
fixes a divide-by-zero bug.

Reported-by:  <syzbot+ce366e2b8296e25d84f5@syzkaller.appspotmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent d7f4d873

drivers/net/usb/cdc_ncm.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -681,8 +681,12 @@ cdc_ncm_find_endpoints(struct usbnet dev, struct usb_interface intf)
		u8 ep;

		for (ep = 0; ep < intf->cur_altsetting->desc.bNumEndpoints; ep++) {

		e = intf->cur_altsetting->endpoint + ep;

		/* ignore endpoints which cannot transfer data */
		if (!usb_endpoint_maxp(&e->desc))
		continue;

		switch (e->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
		case USB_ENDPOINT_XFER_INT:
		if (usb_endpoint_dir_in(&e->desc)) {