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

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[ Upstream commit 3fe4b33513 ]

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>
This commit is contained in:
Bjørn Mork
2019-09-18 14:01:46 +02:00
committed by Greg Kroah-Hartman
parent 337da470bd
commit 941b5eefb1
1 changed files with 5 additions and 1 deletions
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6
drivers/net/usb/cdc_ncm.c
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@@ -679,8 +679,12 @@ 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)) {