From 2cb80187ba065d7decad7c6614e35e07aec8a974 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>
Date: Mon, 6 Nov 2017 15:37:22 +0100
Subject: [PATCH] net: cdc_ether: fix divide by 0 on bad descriptors
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Git-commit: 2cb80187ba065d7decad7c6614e35e07aec8a974
Patch-mainline: v4.14
References: bsc#1067085 CVE-2017-16649
Setting dev->hard_mtu to 0 will cause a divide error in
usbnet_probe. Protect against devices with bogus CDC Ethernet
functional descriptors by ignoring a zero wMaxSegmentSize.
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/net/usb/cdc_ether.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 3e7a3ac3a362..05dca3e5c93d 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -230,7 +230,7 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
goto bad_desc;
}
- if (header.usb_cdc_ether_desc) {
+ if (header.usb_cdc_ether_desc && info->ether->wMaxSegmentSize) {
dev->hard_mtu = le16_to_cpu(info->ether->wMaxSegmentSize);
/* because of Zaurus, we may be ignoring the host
* side link address we were given.
--
2.13.6