From 3fe4b3351301660653a2bc73f2226da0ebd2b95e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>
Date: Wed, 18 Sep 2019 14:01:46 +0200
Subject: [PATCH] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize
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Git-commit: 3fe4b3351301660653a2bc73f2226da0ebd2b95e
Patch-mainline: v5.4-rc1
References: bsc#1051510
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/usb/cdc_ncm.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 50c05d0f44cb..00cab3f43a4c 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -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)) {
--
2.16.4