Patch "net: qmi_wwan: fix divide by 0 on bad descriptors" has been added to the 4.9-stable tree

Patch "net: qmi_wwan: fix divide by 0 on bad descriptors" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net: qmi_wwan: fix divide by 0 on bad descriptors

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-qmi_wwan-fix-divide-by-0-on-bad-descriptors.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Nov 21 13:08:13 CET 2017
From: Bj�rn Mork <bjorn@mork.no>
Date: Mon, 6 Nov 2017 15:32:18 +0100
Subject: net: qmi_wwan: fix divide by 0 on bad descriptors

From: Bj�rn Mork <bjorn@mork.no>


[ Upstream commit 7fd078337201cf7468f53c3d9ef81ff78cb6df3b ]

A CDC Ethernet functional descriptor with wMaxSegmentSize = 0 will
cause a divide error in usbnet_probe:

divide error: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.0-rc8-44453-g1fdc1a82c34f #56
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: usb_hub_wq hub_event
task: ffff88006bef5c00 task.stack: ffff88006bf60000
RIP: 0010:usbnet_update_max_qlen+0x24d/0x390 drivers/net/usb/usbnet.c:355
RSP: 0018:ffff88006bf67508 EFLAGS: 00010246
RAX: 00000000000163c8 RBX: ffff8800621fce40 RCX: ffff8800621fcf34
RDX: 0000000000000000 RSI: ffffffff837ecb7a RDI: ffff8800621fcf34
RBP: ffff88006bf67520 R08: ffff88006bef5c00 R09: ffffed000c43f881
R10: ffffed000c43f880 R11: ffff8800621fc406 R12: 0000000000000003
R13: ffffffff85c71de0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88006ca00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe9c0d6dac CR3: 00000000614f4000 CR4: 00000000000006f0
Call Trace:
 usbnet_probe+0x18b5/0x2790 drivers/net/usb/usbnet.c:1783
 qmi_wwan_probe+0x133/0x220 drivers/net/usb/qmi_wwan.c:1338
 usb_probe_interface+0x324/0x940 drivers/usb/core/driver.c:361
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x522/0x740 drivers/base/dd.c:557

Fix by simply ignoring the bogus descriptor, as it is optional
for QMI devices anyway.

Fixes: 423ce8caab7e ("net: usb: qmi_wwan: New driver for Huawei QMI based WWAN devices")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/usb/qmi_wwan.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -386,7 +386,7 @@ static int qmi_wwan_bind(struct usbnet *
 	}
 
 	/* errors aren't fatal - we can live with the dynamic address */
-	if (cdc_ether) {
+	if (cdc_ether && cdc_ether->wMaxSegmentSize) {
 		dev->hard_mtu = le16_to_cpu(cdc_ether->wMaxSegmentSize);
 		usbnet_get_ethernet_addr(dev, cdc_ether->iMACAddress);
 	}


Patches currently in stable-queue which might be from bjorn@mork.no are

queue-4.9/net-cdc_ether-fix-divide-by-0-on-bad-descriptors.patch
queue-4.9/qmi_wwan-add-missing-skb_reset_mac_header-call.patch
queue-4.9/net-qmi_wwan-fix-divide-by-0-on-bad-descriptors.patch