linux-kernel - [PATCH 4.4 21/99] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20191003154304.368107309@linuxfoundation.org>
Date:   Thu,  3 Oct 2019 17:52:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+ce366e2b8296e25d84f5@...kaller.appspotmail.com,
        Bjørn Mork <bjorn@...k.no>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH 4.4 21/99] cdc_ncm: fix divide-by-zero caused by invalid wMaxPacketSize

From: Bjørn Mork <bjorn@...k.no>

[ 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@...kaller.appspotmail.com
Signed-off-by: Bjørn Mork <bjorn@...k.no>
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/usb/cdc_ncm.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -636,8 +636,12 @@ cdc_ncm_find_endpoints(struct usbnet *de
 	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)) {